Cathode-ray tube and image display comprising the same

ABSTRACT

A cathode ray tube includes an electron gun for emitting at least one electron beam; a mask frame include a mask having a plurality of holes or slits for allowing the electron beam to be transmitted therethrough and a frame to which the mask is attached; and a panel including a phosphor layer to be scanned by the at least one electron beam transmitted through the plurality of holes or slits of the mask. The panel includes a plurality of stud pins for supporting the frame. The frame includes a plurality of elastic supports engaged with the plurality of stud pins. At least one of the plurality of elastic supports includes an engagement portion having an engaging hole which is engaged with one of the plurality of the stud pins and an elastic portion in contact with the one stud pin. Mask frame vibration causes the elastic portion to rub against a respective stud pin so as to generate a frictional force for attenuating the vibration of the mask frame.

TECHNICAL FIELD

The present invention relates to a cathode ray tube, specifically acathode ray tube having a feature in an elastic support used forsupporting a frame, and also relates to an image display apparatus usingsuch a cathode ray tube, such as an image monitor used for a TV, apersonal computer, an oscilloscope or the like.

BACKGROUND ART

FIG. 20A shows a structure of a conventional cathode ray tube 1900. Asshown in FIG. 20A, the cathode ray tube 1900 includes a panel 1903having a generally quadrangular container-shape. The panel 1903 includesa panel main body 1901 having an inner curved surface and a side wall1902 provided around four sides of the panel main body 1901. The cathoderay tube 1900 further includes a funnel 1904 joined to the side wall1902.

On an inner surface of the panel 1903, a phosphor screen 1905 includinga three color phosphor layer of RGB color elements (red, green and blue)is provided. A mask frame 1909 is provided to face the phosphor screen1905. The mask frame 1909 includes a generally quadrangular frame 1908and a mask (shadow mask) 1907 attached to the frame 1908 so as to extendover the frame 1908. The mask 1907 is generally quadrangular and has aplurality of electron beam transmission holes or slits 1906.

The funnel 1904 includes a neck 1910, which accommodates an electron gun1912 for emitting three electron beams 1911. A color image is displayedas follows. The three electron beams 1911 emitted by the electron gun1912 are deflected by a magnetic field generated by a deflection device1913 provided on an outer surface of the funnel 1904, and the phosphorscreen 1905 is horizontally and vertically scanned with the threeelectron beams 1911 through the mask frame 1909. In FIG. 20A, referencenumeral 1906 represents an inner magnetic shield attached to the frame1908. In order to display an accurate color image on the phosphor screen1905 in the cathode ray tube 1900 having the above-described structure,the mask frame 1909 needs to be kept aligned at a prescribedrelationship with respect to the three color phosphor layer included inthe phosphor screen 1905.

FIG. 20B is a cross-sectional view of the cathode ray tube 1900 shown inFIG. 20A taken along line A—A in FIG. 1. As shown in FIG. 20B, a knownsystem for supporting the mask frame 1909 includes generally V-shapedelastic supports 1914 respectively attached to four corners of the frame1908 and stud pins 1915 respectively provided on the four corners of theside wall 1902 of the panel 1903. The mask frame 1909 is detachablysupported to the panel 1903 by engaging the elastic supports 1914 withthe stud pins 1915 respectively.

FIG. 21A shows a structure of another conventional cathode ray tube2000. FIG. 21B is across-sectional view of the cathode ray tube 2000shown in FIG. 20A taken along line B—B in FIG. 21A. Identical elementspreviously discussed with respect to FIGS. 20A and 20B bear identicalreference numerals and the descriptions thereof will be omitted. Asshown in FIG. 21B, another known system for supporting the mask frame1909 includes strip-like elastic supports 2001 respectively attached tocenters of four sides of the frame 1908 and stud pins 1915 respectivelyprovided at centers of four inner faces of the side wall 1902 of thepanel 1903. The mask frame 1909 is detachably supported to the panel1903 by engaging the elastic supports 2001 with the stud pins 1915respectively. This system is generally known.

In general, in order to display a color image with no degradation ofcolor purity on a phosphor screen of a cathode ray tube, it is necessarythat the three electron beams 1911 transmitted through the holes 1906formed in the mask 1907 (shadow mask) of the mask frame 1909 shouldaccurately land on respective color areas of the three color phosphorelements of the phosphor screen 1905. In order to realize this state,the positional relationship between the panel 1903 and the mask frame1909 needs to be kept at a prescribed relationship. Particularly, thedistance (q value) between the inner surface of the panel main body 1901on which the phosphor screen 1905 is provided and a surface of the mask1907 facing the panel main body 1901 (shadow mask surface) needs to bekept within a prescribed tolerance.

In the state where a cathode ray tube (cathode ray tube 2000, forexample) is incorporated in a set such as a TV or an image monitor,vibration from a speaker built into the set or vibration from outsidethe set is transferred to the cathode ray tube through a cabinet of theset, which undesirably causes the frame 1908 and the mask 1907 to alsovibrate through resonance. When the vibration amplitude of the frame1908 and the mask 1907 exceeds the prescribed tolerance of the q value,the three electron beams 1911 land on offset positions and degradationof color purity occurs. As a result, the image quality is deteriorated.

In addition, when the frame 1908 and the mask 1907 vibrate in the planardirection thereof to the extent that one of the transmission holes 1906of the mask 1907 reaches an adjacent transmission hole 1906, the threeelectron beams 1911 do not accurately land on the phosphor layer of thephosphor screen 1905 (mislanding).

In order to restrict the vibration of the mask 1907 and the frame 1908caused by the vibration transferred from outside the cathode ray tube(cathode ray tube 2000, for example), the vibration of the frame 1908first needs to be quickly stopped. The reason for this is that unlessthe frame 1908 stops vibrating, the mask 1907 fixed to the frame 1908does not stop vibrating. The inside of the cathode ray tube 2000 is invacuum and the vibration is not attenuated by friction with air.Therefore, the mask 1907 and the frame 1908 are likely to keep vibratingfor an extended period of time inside the cathode ray tube 2000.Accordingly, in order to restrict the vibration, it is necessary toprovide a structure to cause friction by the vibration inside thecathode ray tube 2000 so that vibration energy is converted intofriction energy.

FIGS. 22A, 22B and 22C show a specific structure of the elastic support1914 shown in FIGS. 20A and 20B, which is disclosed in JapaneseLaid-Open Publication No. 9-293459. The elastic support 1914 includes afixing portion 2101 to be fixed to the frame 1908, an engagement portion2102 having an engaging hole 2104 for engagement with the stud pin 1915(FIGS. 20A and 20B), and connection portions 2103 a and 2103 b forconnecting the fixing portion 2101 and the engagement portion 2102. Theconnection portions 2103 a and 2103 b are fixed to each other at awelding point 2107 by welding. The elastic support 1914 further includesplate-like bent portions 2105 perpendicularly raised from the fixingportion 2101 and slits 2106 made in the engagement portion 2102 forreceiving the bent portions 2105. When the stud pin 1915 is engaged withthe engaging hole 2104, the bent portions 2105 are inserted through theslits 2106. Due to such a structure, when the frame 1908 vibrates, thebent portions 2105 cause friction with inner surfaces of the slits 2106,and thus vibration energy is converted to friction energy. Thus, thevibration of the frame 1908 is restricted.

FIGS. 23A and 23B show a specific structure of the elastic support 2001shown in FIGS. 21A and 21B, which is disclosed in Japanese Laid-OpenPublication No. 9-35653. The elastic support 2001 includes a pluralityof leaf springs having an identical shape (two leaf springs 2002 and2003 in the example shown in FIGS. 23A and 23B), and is provided in thevicinity of a center of each of the four sides of the frame 1908 asshown in FIG. 21B. When the frame 1908 vibrates due to vibrationexternally applied, the elastic support 2001 is deformed and thusfriction is caused between the leaf springs 2002 and 2003. Accordingly,the vibration of the frame 1908 is rapidly attenuated. FIG. 23B showshow the elastic support 2001 is engaged with the stud pin 1915.

The elastic support 1914 shown in FIGS. 22A, 22B and 22C has thefollowing problem.

When the frame 1908 vibrates, both of two surfaces of the bent portions2105 cause friction with inner surfaces of the slits 2106. Accordingly,the vibration is rapidly attenuated. However, when two surfacesperpendicular to each other (surfaces of the bent portions 2105 and theinner surfaces of the slits 2106) rub against each other, the slidingsurfaces need to be highly smooth. Otherwise, the surfaces are easilylocked by each other. Especially the inner space of the cathode raytube, which is in high vacuum, has a friction coefficient larger thanthat in the outside air. Accordingly, there is a high possibility thatthe surfaces of the bent portions 2105 and the inner surfaces of theslits 2106 are locked by each other so as to be unmovable. Once the bentportions 2105 and the slits 2106 become unmovable, the elastic support1914 cannot provide its original function. That is, when the electronbeams 1911 (FIGS. 20A and 20B) hit the mask 1907 to raise thetemperature of the mask 1907 and the mask 1907 expands while the cathoderay tube 1900 is in operation, the elastic support 1914 cannot adjustthe position of the frame 1908 so as to correct the positionalrelationship (q value) between the inner surface of the panel main body1901 on which the phosphor screen 1905 is provided and the surface ofthe mask 1907 facing the panel main body 1901 (shadow mask surface). Thereason for this is that the elastic support 1914 has a mechanism ofcorrecting the position of the frame 1908 by the elasticity of theengagement portion 2102 and the connecting portion 2103 a.

The elastic support 2001 shown in FIGS. 23A and 23B has the followingproblems.

The leaf springs 2002 and 2003 having an identical shape are completelysuperimposed with each other. Accordingly, friction does not occurbetween the leaf springs 2002 and 2003 unless a force sufficiently largeto deform the leaf spring 2002 is applied by the vibration. In addition,since a contact area of the leaf springs 2002 and 2003 is relativelylarge, the friction coefficient between the leaf springs 2002 and 2003is large. For this reason also, the vibration of the frame 1908 cannotbe restricted by the friction unless the vibration has a relativelylarge amplitude. Especially against the vibration in the axial directionof the cathode ray tube, the restriction effect of the elastic support2001 is small due to a very small friction between the leaf springs 2002and 2003. The friction is very small because the leaf springs 2002 and2003 are likely to move in the same manner in a superimposed state dueto a large friction coefficient. In actuality, when the vibrationamplitude of the frame 1908 exceeds, for example, about 100 μm in theaxial direction, the degradation of color purity becomes conspicuous.The leaf spring 2002 does not receive a sufficiently large force inresponse to such a small vibration amplitude, and thus is not deformedmuch. For these reasons, the elastic support 2001 does not provide asufficient effect of restricting the vibration and is not practical foruse.

The present invention has an objective of providing a cathode ray tubefor rapidly attenuating vibration of a frame against vibrationtransferred from outside and thus preventing degradation of color purityin a color image from occurring due to mislanding of electron beams, andan image display apparatus using such a cathode ray tube.

DISCLOSURE OF THE INVENTION

A cathode ray tube according to the present invention includes anelectron gun for emitting at least one electron beam; a mask frameinclude a mask having a plurality of holes or slits for allowing the atleast one electron beam to be transmitted therethrough and a frame towhich the mask is attached; and a panel including a phosphor layer to bescanned by the at least one electron beam transmitted through theplurality of holes or slits of the mask. The panel includes a pluralityof stud pins for supporting the frame. The frame includes a plurality ofelastic supports engaged with the plurality of stud pins. At least oneof the plurality of elastic supports includes an engagement portionhaving an engaging hole which is engaged with one of the plurality ofthe stud pins and an elastic portion in contact with the one stud pin.Mask frame vibration causes the elastic portion to rub against arespective stud pin so as to generate a frictional force for attenuatingthe vibration of the mask frame. The above-described objective can beachieved by this structure.

In one embodiment of the invention, the one stud pin has a tip, and theelastic portion rubs against the tip of the one stud pin.

In one embodiment of the invention, the elastic portion is formed of ametal plate rolled into a cylindrical shape.

In one embodiment of the invention, the elastic portion is formed of ametal plate bent into a leaf spring-shape.

In one embodiment of the invention, the at least one elastic supportincludes a fixing portion for fixing the at least one elastic support tothe frame, and the elastic portion is fixed to the fixing portion.

In one embodiment of the invention, the fixing portion is providedbetween the engagement portion and the frame.

In one embodiment of the invention, the elastic portion is providedbetween the engagement portion and the fixing portion.

In one embodiment of the invention, the at least one elastic supportfurther includes a connection portion for connecting the fixing portionand the engagement portion to each other.

In one embodiment of the invention, a thickness of the fixing portiont0, a thickness of the connection portion t1 and a thickness of theelastic portion t2 satisfy the relationships of t0>t1 and t0≧t2.

In one embodiment of the invention, a thickness of the fixing portiont0, a thickness of the connection portion t1 and a thickness of theelastic portion t2 satisfy the relationships of t0>t1 and t1≧t2.

In one embodiment of the invention, each of the plurality of elasticsupports has a substantially V-shaped cross-section.

In one embodiment of the invention, each of the plurality of elasticsupports has a substantially strip-like shape.

In one embodiment of the invention, the at least one elastic supportfurther includes a connection portion for connecting the fixing portionand the engagement portion to each other, and the elastic portion isfixed to the connection portion.

In one embodiment of the invention, the elastic portion is fixed to theengagement portion.

In one embodiment of the invention, the frame includes a pair of firstshafts and a pair of second shafts shorter than the pair of firstshafts, and the at least one elastic support is provided on at least onefirst shaft of the pair of first shafts.

In one embodiment of the invention, the frame includes a pair of firstshafts and a pair of second shafts shorter than the pair of firstshafts, and the at least one elastic support is provided on at least onesecond shaft of the pair of second shafts.

In one embodiment of the invention, the frame includes a plurality ofcorners, and the plurality of elastic supports are provided atrespective corners.

In one embodiment of the invention, the mask includes a damper providedat an end thereof for attenuating the vibration of the mask.

In one embodiment of the invention, the electron gun includes anelectric field electron emission element for reducing a cross-section ofthe at least one electron beam.

In one embodiment of the invention, the at least one elastic support hasa bimetal structure including a first metal area formed of a first metalhaving a first coefficient of thermal expansion and a second metal areaformed of a second metal having a second coefficient of thermalexpansion which is less than the first coefficient of thermal expansion,the first metal area and the second metal being joined together.

In one embodiment of the invention, the first metal area formed of thefirst metal has a greater longitudinal size than a longitudinal size ofthe second metal area formed of the second metal.

In one embodiment of the invention, the first metal includes stainlesssteel, and the second metal includes nickel steel.

A cathode ray tube according to the present invention includes anelectron gun for emitting at least one electron beam; a mask frameinclude a mask having a plurality of holes or slits for allowing the atleast one electron beam to be transmitted therethrough and a frame towhich the mask is attached; and a panel including a phosphor layer to bescanned by the at least one electron beam transmitted through theplurality of holes or slits of the mask. The panel includes a pluralityof stud pins for supporting the frame. The frame includes a plurality ofelastic supports engaged with the plurality of stud pins. At least oneof the plurality of elastic supports includes an engagement portionhaving an engaging hole which is engaged with one of the plurality ofstud pins. The engagement portion includes a plurality of sliding piecesforming a funnel shape provided in the engaging hole. Mask framevibration causes a surface of each of the plurality of sliding pieces torub against a respective stud pin so as to generate a frictional forcefor attenuating the vibration of the mask frame. The above-describedobjective can be achieved by this structure.

In one embodiment of the invention, the at least one elastic supportincludes a fixing portion for fixing the at least one elastic support tothe frame, and a connection portion for connecting the fixing portionand the engagement portion.

In one embodiment of the invention, the sliding piece has a length ofabout 0.5 mm or more and about 2.5 mm or less.

In one embodiment of the invention, each of the plurality of elasticsupports has a substantially strip-like shape.

In one embodiment of the invention, the mask includes a damper providedat an end thereof for attenuating the vibration of the mask.

In one embodiment of the invention, the electron gun includes anelectric field electron emission element for reducing a cross-section ofthe at least one electron beam.

A cathode ray tube according to the present invention includes anelectron gun for emitting at least one electron beam; a mask frameinclude a mask having a plurality of holes or slits for allowing the atleast one electron beam to be transmitted therethrough and a frame towhich the mask is attached; and a panel including a phosphor layer to bescanned by the at least one electron beam transmitted through theplurality of holes or slits of the mask. The panel includes a pluralityof stud pins for supporting the frame. The frame includes a plurality ofelastic supports engaged with the plurality of stud pins. At least oneof the plurality of elastic supports includes an engagement portionhaving an engaging hole which is engaged with one of the plurality ofstud pins. The engagement portion includes a central portion having theengaging hole, a first side portion separated from the central portionby a first cut, and a second side portion separated from the centralportion by a second cut formed on an opposite side to the first cut withrespect to the central portion. Mask frame vibration causes a cutsectional face of the central portion facing the first cut to rubagainst a cut sectional face of the first side portion so as to generatea frictional force for attenuating the vibration of the mask frame. Maskframe vibration further causes another cut sectional face of the centralportion facing the second cut to rub against a cut sectional face of thesecond side portion so as to generate a frictional force for attenuatingthe vibration of the mask frame. The above-described objective can beachieved by this structure.

In one embodiment of the invention, the at least one elastic supportincludes a fixing portion for fixing the at least one elastic support tothe frame, and a connection portion for connecting the fixing portionand the engagement portion to each other.

In one embodiment of the invention, each of the plurality of elasticsupports has a substantially V-shaped cross-section.

In one embodiment of the invention, the mask includes a damper providedat an end thereof for attenuating the vibration of the mask.

In one embodiment of the invention, the electron gun includes anelectric field electron emission element for reducing a cross-section ofthe at least one electron beam.

A cathode ray tube according to the present invention includes anelectron gun for emitting at least one electron beam; a mask frameinclude a mask having a plurality of holes or slits for allowing the atleast one electron beam to be transmitted therethrough and a frame towhich the mask is attached; and a panel including a phosphor layer to bescanned by the at least one electron beam transmitted through theplurality of holes or slits of the mask. The panel includes a pluralityof stud pins for supporting the frame. The frame includes a plurality ofelastic supports engaged with the plurality of stud pins. At least oneof the plurality of elastic supports includes an engagement portionhaving an engaging hole which is engaged with one of the plurality ofstud pins and a fixing portion for fixing the at least one elasticsupport to the frame. The fixing portion includes a first bent portionand a second bent portion bent towards the engagement portion. Theengagement portion includes a third bent portion bent so as to be incontact with the first bent portion and a fourth bent portion bent so asto be in contact with the second first bent portion. Mask framevibration causes the first bent portion to rub against the third bentportion so as to generate a frictional force for attenuating thevibration of the mask frame. The mask frame vibration further causes thesecond bent portion to rub against the fourth bent portion so as togenerate a frictional force for attenuating the vibration of the maskframe so as to generate a frictional force for attenuating the vibrationof the mask frame. The above-described objective can be achieved by thisstructure.

In one embodiment of the invention, the at least one elastic supportfurther includes a connection portion for connecting the fixing portionand the engagement portion to each other.

In one embodiment of the invention, each of the plurality of elasticsupports has a substantially V-shaped cross-section.

In one embodiment of the invention, the first bent portion has a fifthbent portion for restricting the engagement portion from moving in adirection away from the fixing portion, and the second bent portion hasa sixth bent portion for restricting the engagement portion from movingtowards the fixing portion.

In one embodiment of the invention, the frame includes a plurality ofcorners, and the plurality of elastic supports are provided atrespective corners.

In one embodiment of the invention, the frame includes a pair of firstshafts and a pair of second shafts shorter than the pair of firstshafts, and the at least one elastic support is provided on at least onefirst shaft of the pair of first shafts.

In one embodiment of the invention, the frame includes a pair of firstshafts and a pair of second shafts shorter than the pair of firstshafts, and the at least one elastic support is provided on at least onesecond shaft of the pair of second shafts.

In one embodiment of the invention, the mask includes a damper providedat an end thereof for attenuating the vibration of the mask.

In one embodiment of the invention, the electron gun includes anelectric field electron emission element for reducing a cross-section ofthe at least one electron beam.

A cathode ray tube according to the present invention includes anelectron gun for emitting at least one electron beam; a mask frameinclude a mask having a plurality of holes or slits for allowing the atleast one electron beam to be transmitted therethrough and a frame towhich the mask is attached; and a panel including a phosphor layer to bescanned by the at least one electron beam transmitted through theplurality of holes or slits of the mask. The panel includes a pluralityof stud pins for supporting the frame. The frame includes a plurality ofelastic supports engaged with the plurality of stud pins. At least oneof the plurality of elastic supports includes an engagement portionhaving an engaging hole which is engaged with one of the plurality ofthe stud pins, a fixing portion for fixing the at least one elasticsupport to the frame, and a connection portion for connecting the fixingportion and the engagement portion to each other. An area of the fixingportion S1, an area of the connection portion S2, and an area of theengagement portion S3 satisfy the relationships of S1≧S2 and S1≧S3. Theabove-described objective can be achieved by this structure.

In one embodiment of the invention, the fixing portion has a firstsurface which is in contact with the frame and has a rough portion. Theframe has a second surface which is in contact with the fixing portionand has a rough portion. The first surface and the second surface arefixed to each other by welding.

In one embodiment of the invention, the frame includes an attachmentplate for fixing the fixing portion.

In one embodiment of the invention, the fixing portion has a firstsurface which is in contact with the attachment plate and has a roughportion. The attachment plate has a second surface which is in contactwith the fixing portion and has a rough portion. The first surface andthe second surface are fixed to each other by welding.

In one embodiment of the invention, the fixing portion includes awelding area fixed to the frame by welding, and the welding area isprovided on an opposite side to the connection portion with respect to acentral border of the fixing portion.

In one embodiment of the invention, an area of the fixing portion S1, anarea of the connection portion S2 and an area of the engagement portionS3 satisfy the relationship of S1≧S2≧S3.

In one embodiment of the invention, the fixing portion includes a bentportion bent towards the frame.

In one embodiment of the invention, each of the plurality of elasticsupports has a substantially V-shaped cross-section.

In one embodiment of the invention, each of the plurality of elasticsupports has a substantially strip-like shape.

In one embodiment of the invention, a ratio of a total area of the atleast one elastic support and a weight of the frame is about 5 cm²/kg ormore.

In one embodiment of the invention, the frame includes a pair of firstshafts and a pair of second shafts shorter than the pair of firstshafts, and the at least one elastic support is provided on at least onefirst shaft of the pair of first shafts.

In one embodiment of the invention, the frame includes a pair of firstshafts and a pair of second shafts shorter than the pair of firstshafts, and the at least one elastic support is provided on at least onesecond shaft of the pair of second shafts.

In one embodiment of the invention, the frame includes a plurality ofcorners, and the plurality of elastic supports are provided atrespective corners.

In one embodiment of the invention, the at least one elastic support hasa bimetal structure including a first metal area formed of a first metalhaving a first coefficient of thermal expansion and a second metal areaformed of a second metal having a second coefficient of thermalexpansion which is less than the first coefficient of thermal expansion,the first metal area and the second metal being joined together.

In one embodiment of the invention, the first metal area formed of, thefirst metal has a greater longitudinal size than a longitudinal size ofthe second metal area formed of the second metal.

In one embodiment of the invention, the mask includes a damper providedat an end thereof for attenuating vibration of the mask.

In one embodiment of the invention, the electron gun includes anelectric field electron emission element for reducing a cross-section ofthe at least one electron beam.

A cathode ray tube according to the present invention includes anelectron gun for emitting at least one electron beam; a mask frameinclude a mask having a plurality of holes or slits for allowing the atleast one electron beam to be transmitted therethrough and a frame towhich the mask is attached; and a panel including a phosphor layer to bescanned by the at least one electron beam transmitted through theplurality of holes or slits of the mask. The panel includes a first studpin and a second stud pin for supporting the frame. The frame includes afirst elastic support and a second elastic support respectively engagedwith the first stud pin and the second stud pin. The first stud pinpressurizes the first elastic support with a first pressure, and thesecond stud pin pressurizes the second elastic support with a secondpressure which is substantially different from the first pressure. Theabove-described objective can be achieved by this structure.

In one embodiment of the invention, the first pressure and the secondpressure are each about 5 N or more and about 100 N or less.

In one embodiment of the invention, the first elastic support and thesecond elastic support each have a spring coefficient of about 1 N/mm ormore and about 25 N/mm or less.

In one embodiment of the invention, the frame includes a pair of firstshafts and a pair of second shafts shorter than the pair of firstshafts, and the at least one elastic support is provided on at least onefirst shaft of the pair of first shafts.

In one embodiment of the invention, the frame includes a pair of firstshafts and a pair of second shafts shorter than the pair of firstshafts, and the at least one elastic support is provided on at least onesecond shaft of the pair of second shafts.

In one embodiment of the invention, the frame includes a plurality ofcorners, and the plurality of elastic supports are provided atrespective corners.

In one embodiment of the invention, the at least one elastic support hasa bimetal structure including a first metal area formed of a first metalhaving a first coefficient of thermal expansion and a second metal areaformed of a second metal having a second coefficient of thermalexpansion which is less than the first coefficient of thermal expansion,the first metal area and the second metal being joined together.

In one embodiment of the invention, the first metal area formed of thefirst metal has a greater longitudinal size than a longitudinal size ofthe second metal area formed of the second metal.

In one embodiment of the invention, each of the plurality of elasticsupports has a substantially V-shaped cross-section.

In one embodiment of the invention, each of the plurality of elasticsupports has a substantially strip-like shape.

In one embodiment of the invention, the mask includes a damper providedat an end thereof for attenuating the vibration of the mask.

In one embodiment of the invention, the electron gun includes anelectric field electron emission element for reducing a cross-section ofthe at least one electron beam.

A cathode ray tube according to the present invention includes anelectron gun for emitting at least one electron beam; a mask frameinclude a mask having a plurality of holes or slits for allowing the atleast one electron beam to be transmitted therethrough and a frame towhich the mask is attached; and a panel including a phosphor layer to bescanned by the at least one electron beam transmitted through theplurality of holes or slits of the mask. The panel includes a pluralityof stud pins for supporting the frame. The frame includes a plurality ofelastic supports engaged with the plurality of stud pins. At least oneof the plurality of elastic supports includes an engagement portionhaving an engaging hole which is engaged with one of the plurality ofstud pins and an elastic portion in contact with the engagement portion.Mask frame vibration causes the elastic portion to rub against theengagement portion so as to generate a frictional force for attenuatingthe vibration of the mask frame so as to generate a frictional force forattenuating the vibration of the mask frame. The above-describedobjective can be achieved by this structure.

In one embodiment of the invention, the elastic portion is provided oneach of both sides of the engaging hole.

In one embodiment of the invention, the elastic portion is a metal platerolled into a cylindrical shape.

In one embodiment of the invention, the elastic portion is formed of ametal plate bent into a leaf spring-shape.

In one embodiment of the invention, the at least one elastic supportincludes a fixing portion for fixing the at least one elastic support tothe frame, and the elastic portion is fixed to the fixing portion.

In one embodiment of the invention, each of the plurality of elasticsupports has a substantially V-shaped cross-section.

In one embodiment of the invention, the mask includes a damper providedat an end thereof for attenuating the vibration of the mask.

In one embodiment of the invention, the electron gun includes anelectric field electron emission element for reducing a cross-section ofthe at least one electron beam.

An image display apparatus according to the present invention includeseach of the above-described cathode ray tubes. The above-describedobjective can be achieved by this structure.

According to one aspect of the invention, a cathode ray tube forsubstantially eliminating mislanding of electron beams can be providedsince even when the frame vibrates, friction is generated between anelastic portion of an elastic support and a stud pin on the frame, whichrapidly attenuates the vibration of the frame.

According to another aspect of the invention, a cathode ray tube forsubstantially eliminating mislanding of electron beams can be providedsince even when the frame vibrates, friction is generated between aplurality of sliding pieces forming a funnel shape of an elastic supportand a stud pin on the frame, which rapidly attenuates the vibration ofthe frame.

According to still another aspect of the invention, a cathode ray tubefor substantially eliminating mislanding of electron beams can beprovided since even when the frame vibrates, a cut sectional face of acentral portion of an elastic support and a cut sectional face of eachof side portions of the elastic support rub against each other, whichrapidly attenuates the vibration of the frame.

According to still another aspect of the invention, a cathode ray tubefor substantially eliminating mislanding of electron beams can beprovided since even when the frame vibrates, bent portions of an elasticsupport rub against each other, which rapidly attenuates the vibrationof the frame.

According to still another aspect of the invention, a cathode ray tubefor substantially eliminating mislanding of electron beams can beprovided since even when the frame vibrates, a fixing portion of anelastic support having the largest area rubs against the frame, whichrapidly attenuates the vibration of the frame.

According to still another aspect of the invention, a cathode ray tubefor substantially eliminating mislanding of electron beams can beprovided since even when a strong impact such as an impact applied by apackage dropping test is applied, a fixing portion of an elastic supportand the frame which are welded together are prevented from beingdetached from each other, which rapidly attenuates the vibration of theframe.

According to still another aspect of the invention, the distance betweena welded area of the fixing portion and the engagement portion of anelastic support is extended, which can effectively restrict mislandingof the electron beams caused by a temperature rise while the cathode raytube is in operation. A non-welded area of the fixing portion which isbetween the welded area and the connection portion can be enlarged. Whenthe frame vibrates, friction is generated between the non-welded areaand the fixing portion. Therefore, the vibration of the frame can berapidly attenuated.

According to still another aspect of the invention, the internal stressof a plurality of elastic supports can be different. Therefore, even theelastic supports having the same shape can be different in naturalfrequency and thus in resonance frequency. Thus, the vibration of theframe can be rapidly attenuated.

According to still another aspect of the invention, vibration energy ofthe mask of the cathode ray tube can be converted into friction energyby a damper, which rapidly attenuates the vibration of the frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic view of a cathode ray tube in Example 1 accordingto the present invention.

FIG. 1B shows a mask frame supporting device shown in FIG. 1A.

FIG. 1C shows a structure of the mask frame shown in FIG. 1A.

FIG. 2A is a schematic view of an elastic support in the cathode raytube in Example 1.

FIG. 2B is a side view of the elastic support in the cathode ray tube inExample 1.

FIG. 3A is a schematic view of an elastic support in a cathode ray tubein Example 2.

FIG. 3B is a side view of the elastic support in the cathode ray tube inExample 2.

FIG. 4A is a schematic view of an elastic support in a cathode ray tubein Example 3.

FIG. 4B is a side view of the elastic support in the cathode ray tube inExample 3.

FIG. 5A is a schematic view of an elastic support in a cathode ray tubein Example 4.

FIG. 5B is a side view of the elastic support in the cathode ray tube inExample 4.

FIG. 6 is a schematic view of an elastic support in a cathode ray tubein Example 5.

FIG. 7A is a schematic view of an elastic support in a cathode ray tubein Example 6.

FIG. 7B is a side view of the elastic support in the cathode ray tube inExample 6.

FIG. 8A is a schematic view of a cathode ray tube in Example 7 accordingto the present invention.

FIG. 8B shows a mask frame supporting device shown in FIG. 8A.

FIG. 8C shows a structure of the mask frame shown in FIG. 8A.

FIG. 9A is a schematic view of an elastic support in the cathode raytube in Example 7.

FIG. 9B is a plan view of the elastic support in the cathode ray tube inExample 7.

FIG. 10A is a schematic view of an elastic support in a cathode ray tubein Example 8.

FIG. 10B is a plan view of the elastic support in the cathode ray tubein Example 8.

FIG. 11A is a schematic view of an elastic support in a cathode ray tubein Example 9.

FIG. 11B is a plan view of the elastic support in the cathode ray tubein Example 9.

FIG. 12A is a schematic view of an elastic support in a cathode ray tubein Example 10.

FIG. 12B is a plan view of the elastic support in the cathode ray tubein Example 10.

FIG. 13A is a schematic view of the elastic support in the cathode raytube in Examples 11 through 13 and 20.

FIG. 13B is a plan view of the elastic support in the cathode ray tubein Examples 11 through 13 and 20.

FIG. 14 is a schematic view of an elastic support in a cathode ray tubein Example 14.

FIG. 15A is a schematic view of an elastic support in a cathode ray tubein Example 15.

FIG. 15B is a plan view of the elastic support in the cathode ray tubein Example 15.

FIG. 16A is a schematic view of an elastic support in a cathode ray tubein Examples 16, 17 and 21.

FIG. 16B is a plan view of the elastic support in the cathode ray tubein Examples 16, 17 and 21.

FIG. 17A is a schematic view of an elastic support in a cathode ray tubein Example 18.

FIG. 17B is a plan view of the elastic support in the cathode ray tubein Example 18.

FIG. 18 is a schematic view of an elastic support in a cathode ray tubein Examples 19 and 21.

FIG. 19 is a schematic view of a damper in a cathode ray tube in Example21.

FIG. 20A is a schematic view of a conventional cathode ray tube.

FIG. 20B shows a mask frame supporting device shown in FIG. 20A.

FIG. 21A is a schematic view of another conventional cathode ray tube.

FIG. 21B shows a mask frame supporting device shown in FIG. 21A.

FIG. 22A is a bottom view of a conventional elastic support shown inFIG. 22A.

FIG. 22B is a front view of the conventional elastic support shown inFIG. 22A.

FIG. 22C is a side view of the conventional elastic support shown inFIG. 22A.

FIG. 23A is a schematic view of another conventional elastic support.

FIG. 23B is a cross-sectional view of the another conventional elasticsupport shown in FIG. 23A.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described by way of exampleswith reference to drawings.

EXAMPLE 1

FIG. 1A shows a cathode ray tube 100 in Example 1 according to thepresent invention. FIG. 1B is a cross-sectional view of the cathode raytube 100 shown in FIG. 1A taken along lines C—C in FIG. 1A. The cathoderay tube 100 includes a substantially quadrangular panel 103 having aneffective display section 101 and a side wall 102 provided around foursides thereof, and a funnel 105 including a neck 104.

On an inner surface of the effective display section 101 of the panel103, a phosphor screen 106 is provided. The phosphor screen 106 includesthree color phosphor elements respectively providing red (R), green (G)and blue (B) light, which are arranged two-dimensionally. A mask frame110 is engaged with the panel 103 so as to face the phosphor screen 106by a mask frame supporting device described later. The mask frame 110includes a frame 109 and a substantially quadrangular mask 108 attachedto the frame 109. The mask 108 has a gradual curved surface, which has aplurality of electron beam transmission holes (or slits) 107.

FIG. 1C is an isometric view of the mask frame 110. As shown in FIG. 1C,the frame 109 of the mask frame 110 includes two first shafts 109 a andtwo second shafts 109 b. The first shafts 109 a are longer than thesecond shafts 109 b. The first shafts 109 a each have a triangular (orL-shaped) cross-section and are formed of an Fe-Ni alloy. The two secondshafts 109 b each have a generally U-shaped (or L-shaped, quadrangularor polygonal) cross-section and are formed of an Fe-Ni alloy. The mask108 is welded to and extended between the two first shafts 109 a.Generally, the mask 108 is formed of the same material as that of theframe 109. When a type of the Fe-Ni alloy which contains 36 wt. % of Ni(commercially referred to as “Invar”) is used, the coefficient ofthermal expansion can be reduced and thus the thermal deformation inoperation can be minimized. The frame 109 is provided with an innermagnetic shield 111 (FIG. 1A) for shielding an external magnetic fieldsuch as geomagnetism.

The neck 104 of the funnel 105 accommodates an electron gun 114 foremitting three electron beams 112, and a deflection yoke 113 is providedon an outer surface of the funnel 105. A color image is displayed bydeflecting the three electron beams 112 by a magnetic field generated bythe deflection yoke 113 and horizontally and vertically scanning thephosphor screen 106 with the three electron beams 112 through the mask108.

The mask frame supporting device for engaging the mask frame 110 withthe panel 103 will be described with reference to FIG. 1B. The maskframe supporting device includes stud pins 115 respectively attached tofour inner faces of the side wall 102 of the panel 103, and elasticsupports 116 respectively fixed to the two first shafts 109 a and thetwo second shafts 109 b of the frame 109. Each stud pin 115 is attachedto a substantially central position of the respective inner face of theside wall 102, and each elastic support 116 is fixed to a substantiallycentral position of the respective shaft 109 a or 109 b. The elasticsupports 116 are formed of stainless steel or an MN-15M alloy. Theelastic supports 116 and the stud pins 115 are respectively detachablyengaged with each other.

Referring to FIG. 1C, each elastic support 116 is fixed to therespective shaft 109 a or 109 b by, for example, welding through anattachment plate 117 at a position where the elastic support 116 can beaccurately engaged with a respective stud pin 115. Each attachment plate117 is directly fixed to the respective shaft 109 a or 109 b by welding.

FIG. 2A is an isometric view of the elastic support 116, and FIG. 2B isa side view of the elastic support 116. The description below will bedone regarding one elastic support 116 for convenience unless specifiedotherwise.

As shown in FIGS. 2A and 2B, the elastic support 116 includes a fixingportion 201 to be fixed to the substantially central position of therespective shaft 109 a or 109 b by welding or the like, an engagementportion 203 including a flat surface having an engaging hole 202 throughwhich the stud pin 115 is inserted, and a connection portion 204 whichis inclined with respect to the fixing portion 201 and the engagementportion 203 for connecting the fixing portion 201 and the engagementportion 203 together. The connection portion 204 and the engagementportion 203 are bent with respect to each other along a bending edge207. The connection portion 204 is shown as being flat in FIGS. 2A and2B, but can be curved. The connection portion 204 can be curved by aplurality of bending edges which are parallel to the bending edge 207.The connection portion 204 can have a hole 205 for reducing a springcoefficient of the engagement portion 203 so as to facilitate thedetachment of the mask frame 109 from the panel 103. The engagementportion 203 and the connection portion 204 are integrally formed bybending processing, and the connection portion 204 and the fixingportion 201 are joined to each other by welding respective ends thereof.Welding points 208 are indicated with an “X”.

The elastic support 116 further includes an elastic portion 206 formedof a metal plate rolled into a cylindrical shape. The elastic portion206 is fixed to the fixing portion 201 at a point 209 by welding or thelike. When the stud pin 115 is inserted through the engaging hole 202, atip 115 a of the stud pin 115 is constantly in contact with the elasticportion 206. Accordingly, when the mask frame 110 vibrates in axialdirections of the cathode ray tube 100 (in directions indicated by thetwo-headed arrow B1 in FIG. 1A, i.e., in directions indicated by thetwo-headed arrow B2 in FIG. 2B), the tip 115 a of the stud pin 115 rubsagainst the elastic portion 206. At this point, vibration energy isconverted into friction energy, and thus the vibration of the mask frame110 is rapidly attenuated.

When the mask frame 110 vibrates in planar directions (directionsperpendicular to the directions indicated by the two-headed arrow B1 inFIG. 1A), the frame 109 pushes and pulls the elastic support 116.Therefore, the elastic support 116 moves the frame 109 in the axialdirections. As a result, an effect similar to the above-described effectis obtained.

The cathode ray tube 100 having the above-described structure wasincorporated into a commercially available TV. While each ofsingle-color images of R, G and B was displayed, the frequency of anattached speaker was swept from 70 Hz to 15000 Hz at an output of 10 W.No degradation of color purity was observed.

For comparison, a comparative cathode ray tube (not shown; referred toas “cathode ray tube (1)” for convenience) having the same structure asthat of the cathode ray tube 100 except that the elastic supports do nothave elastic portions was incorporated into a commercially available TVand vibration of the above-described speaker was applied to thecomparative cathode ray tube (1). A degradation of color purity wasobserved in the image due to vibration of a frequency of even 80 Hz to130 Hz. Even after the vibration of the speaker was stopped, thedegradation of color purity caused by the vibration of the mask framewas still observed for several seconds or longer.

Based on these results, it is considered that the cathode ray tube 100having the structure in Example 1 did not cause degradation of colorpurity for the following reason. When the mask frame 110 was vibrateddue to the vibration of the speaker, the elastic portion 206 of eachelastic support 116 rubbed against the tip 115 a of a respective studpin 115, and the friction between the elastic portion 206 and the tip115 a rapidly attenuated the vibration, thus preventing degradation ofcolor purity.

In the above example, all four of the elastic supports 116 have thestructure shown in FIGS. 2A and 2B. A similar effect is provided when atleast one of the four elastic supports is the elastic support 116 shownin FIGS. 2A and 2B while the other elastic supports do not have anyelastic portion 206.

The fixing portion 201 has a thickness of about 0.3 mm or more,preferably about 1 mm or more, and in consideration of weight and cost,about 3 mm or less. The connection portion 204 and the engagementportion 203 each have a thickness of about 0.3 mm or more and preferablyless than the thickness of the fixing portion 201. The thickness of eachof the connection portion 204 and the engagement portion 203 ispreferably about 1 mm or less in order to have an appropriate level ofelasticity so that the mask frame 110 can be relatively easily detachedfrom the panel 103 during the production process. The elastic portion206 preferably has a thickness of equal to or less than the thickness ofthe connection portion 204 and the engagement portion 203, and morepreferably about 0.05 mm or more and about 0.3 mm or less. The elasticportion 206 may be opened or closed at each of two ends of thecylindrical shape.

A thousand or more cathode ray tubes 100 in Example 1 were produced, andno trouble was experienced in detaching the mask frame 110 from thepanel 103 during the process of forming the phosphor layer, such thatthe yield of the cathode ray tube 100 was 100%.

EXAMPLE 2

In Example 2 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 1A through 1C includes elasticsupports 116A shown in FIGS. 3A and 3B instead of the elastic supports116 shown in FIGS. 2A and 2B. Identical elements previously discussedwith respect to FIGS. 2A and 2B bear identical reference numerals andthe descriptions thereof will be omitted. The description below will bedone regarding one elastic support 116A for convenience unless specifiedotherwise.

The elastic support 116A includes an elastic portion 301 having adifferent structure from that of the elastic portion 206. The elasticportion 301 is a metal plate bent into a leaf spring shape. One of twoends of the elastic portion 301 is fixed to the fixing portion 201 bywelding. As in the structure shown in FIGS. 2A and 2B, when the stud pin115 is inserted through the engaging hole 202, the tip 115 a of the studpin 115 is constantly in contact with the elastic portion 301.

When the mask frame 110 (FIG. 1A) vibrates in directions indicated bythe two-headed arrow B2 in FIG. 3B, the tip 115 a of the stud pin 115rubs against the elastic portion 301 to cause friction. Thus, thevibration of the mask frame 110 is rapidly attenuated.

The cathode ray tube including the elastic supports 116A wasincorporated into a commercially available TV, and vibration of aspeaker was applied as in Example 1. No degradation of color purity wasobserved. The thicknesses of the fixing portion 201, the connectionportion 204, the engagement portion 203, and the elastic portion 301 aresubstantially the same as those in Example 1.

EXAMPLE 3

In Example 3 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 1A through 1C includes elasticsupports 116B shown in FIGS. 4A and 4B instead of the elastic supports116 shown in FIGS. 2A and 2B. Identical elements previously discussedwith respect to FIGS. 2A and 2B bear identical reference numerals andthe descriptions thereof will be omitted. The description below will bedone regarding one elastic support 116B for convenience unless specifiedotherwise.

The elastic support 116B includes an elastic portion 401 having adifferent structure from that of the elastic portion 206. The elasticportion 401 includes two metal plates each rolled into a cylindricalshape. The two metal plates in the cylindrical shape are fixed to thefixing portion 201 by welding so as to have the engaging hole 202interposed. When the stud pin (not shown) is inserted through theengaging hole 202, an outer surface 402 of each elastic portion 401 andan inner surface 403 of the engagement portion 203 are constantly incontact with each other.

Accordingly, when the mask frame 110 (FIG. 1A) vibrates in directionsindicated by the two-headed arrow B2 in FIG. 4B, the inner surface 403of the engagement portion 203 rubs against the outer surface 402 in eachelastic portion 401 to cause friction. Thus, the vibration of the maskframe 110 is rapidly attenuated.

When the mask frame 110 vibrates in planar directions (directionsperpendicular to the directions indicated by the two-headed arrow B1),the vibration of the mask frame 110 is restricted as described inExample 1.

The cathode ray tube including the elastic supports 116B wasincorporated into a commercially available TV, and vibration of aspeaker was applied as in Example 1. No degradation of color purity wasobserved. The thicknesses of the fixing portion 201, the connectionportion 204, the engagement portion 203, and the elastic portion 401 aresubstantially the same as those in Example 1.

A combined use of the elastic support 116B and the elastic portion 206(Example 1) and/or 301 (Example 2) can enhance the attenuation effect ofthe vibration of the mask frame 110. The elastic portion 401 may befixed to the connection portion 204 or the engagement portion 203instead of being fixed to the fixing portion 201, such that a similareffect can be provided.

EXAMPLE 4

In Example 4 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 1A through 1C includes elasticsupports 116C shown in FIGS. 5A and 5B instead of the elastic supports116 shown in FIGS. 2A and 2B. Identical elements previously discussedwith respect to FIGS. 2A and 2B bear identical reference numerals andthe descriptions thereof will be omitted. The description below will bedone regarding one elastic support 116C for convenience unless specifiedotherwise.

The elastic support 116C includes an elastic portion 501 having adifferent structure from that of the elastic portion 206. The elasticportion 501 includes two metal plates each bent into a leaf springshape. The two metal plates in the leaf spring shape are each fixed tothe fixing portion 201 along an end thereof by welding so as to have theengaging hole 202 interposed. When the stud pin 115 (not shown) isinserted through the engaging hole 202, an outer surface 502 of eachelastic portion 501 and an inner surface 503 of the engagement portion203 are constantly in contact with each other.

Accordingly, when the mask frame 110 (FIG. 1A) vibrates in directionsindicated by the two-headed arrow B2 in FIG. 5B and the directionsperpendicular thereto, the inner surface 503 of the engagement portion203 rubs against the outer surface 502 in each elastic portion 501 tocause friction. Thus, the vibration of the mask frame 110 is rapidlyattenuated.

The cathode ray tube including the elastic supports 116C wasincorporated into a commercially available TV, and vibration of aspeaker was applied as in Example 1. No degradation of color purity wasobserved. The thicknesses of the fixing portion 201, the connectionportion 204, the engagement portion 203, and the elastic portion 501 aresubstantially the same as those in Example 1.

A combined use of the elastic support 116C and the elastic portion 206(Example 1) and/or 301 (Example 2) can enhance the attenuation effect ofthe vibration of the mask frame 110.

EXAMPLE 5

In Example 5 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 1A through 1C includes elasticsupports 116D shown in FIG. 6 instead of the elastic supports 116 shownin FIGS. 2A and 2B. Identical elements previously discussed with respectto FIGS. 2A and 2B bear identical reference numerals and thedescriptions thereof will be omitted. The description below will be doneregarding one elastic support 116D for convenience unless specifiedotherwise.

The elastic support 116D has two cuts 601 a and 601 b so as to have theengaging hole 202 interposed. That is, the engagement portion 203 isdivided into a central portion 602 and two side portions 603 a and 603 bby the cuts 601 a and 601 b, respectively.

Accordingly, when the mask frame 110 (FIG. 1A) vibrates in directionsindicated by the two-headed arrow B2 in FIG. 5B and directionsperpendicular thereto, the central portion 602 and the side portions 603a and 603 b move differently from each other. Thus, a cut sectional faceof the central portion 602 facing the side portion 603 a rubs against acut sectional face of the side portion 603 a so as to cause friction,and a cut sectional face of the central portion 602 facing the sideportion 603 b rubs against a cut sectional face of the side portion 603b so as to cause friction. As a result, the vibration of the mask frame110 is rapidly attenuated.

The cathode ray tube including the elastic supports 116D wasincorporated into a commercially available TV, and vibration of aspeaker was applied as in Example 1. No degradation of color purity wasobserved. The thicknesses of the fixing portion 201, the connectionportion 204, the engagement portion 203, and the elastic portion 601 aresubstantially the same as those in Example 1.

A combined use of the elastic supports 116D in Example 5 and the elasticportion 206 (Example 1) and/or 301 (Example 2) can enhance theattenuation effect of the vibration of the mask frame 110.

EXAMPLE 6

In Example 6 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 1A through 1C includes elasticsupports 116E shown in FIGS. 7A and 7B instead of the elastic supports116 shown in FIGS. 2A and 2B. Identical elements previously discussedwith respect to FIGS. 2A and 2B bear identical reference numerals andthe descriptions thereof will be omitted. The description below will bedone regarding one elastic support 116E for convenience unless specifiedotherwise.

In the elastic support 116E, the fixing portion 201 includes two bentportions 701 and 702 bent towards the engagement portions 203, and theengagement portion 203 includes two bent portions 703 and 704 benttowards the fixing portion 201. As best shown in FIG. 7B, the bentportion 702 covers the bent portion 704 so that an inner surface 711 ofthe bent portion 702 is in contact with an outer surface 712 of the bentportion 704. The bent portion 703 covers the bent portion 701 so that aninner surface 714 of the bent portion 703 is in contact with an outersurface 713 of the bent portion 701.

Accordingly, when the mask frame 110 (FIG. 1A) vibrates in directions inFIG. 7A indicated by the double-headed arrow B2 (i.e. directionsperpendicular to the sheet of FIG. 7B) and directions parallel to thesheet of FIG. 7B, the inner surface 711 of the bent portion 702 rubsagainst the outer surface 712 of the bent portion 704 to cause friction,and the inner surface 714 of the bent portion 703 rubs against the outersurface 713 of the bent portion 701 to cause friction. As a result, thevibration of the mask frame 110 is rapidly attenuated.

The bent portion 702 includes a further bent portion 705 bent so as topartially cover an outer surface 715 of the engagement portion 203. Theengagement portion 203 includes an extended portion 706 extending to thebent portion 703, and the bent portion 701 includes a further bentportion 717. Due to such a structure, the elastic support 116E hasanother function of preventing an excessive deformation of the elasticsupport 116E and thus preventing the electron beams from landing atunintended, shifted positions when a large external impact caused by apackage dropping test, for example, is applied to the cathode ray tube.This function is provided by the following principle.

When the elastic support 116E receives an impact which moves theengagement portion 203 away from the fixing portion 201, the bentportion 705 touches the outer surface 715 of the engagement portion 203,restricting the engagement portion 203 from moving away from the fixingportion 201. When the elastic support 116E receives an impact whichmoves the engagement portion 203 towards the fixing portion 201, aninner surface 716 of the extended portion 706 touches the bent portion717, restricting the engagement portion 203 from moving towards thefixing portion 201.

The cathode ray tube including the elastic supports 116E wasincorporated into a commercially available TV, and vibration of aspeaker was applied as in Example 1. No degradation of color purity wasobserved. The TV was dropped from a prescribed height in variousorientations. No degradation of color purity was observed. The test wasrepeated several times. Unlike the conventional elastic support 1914shown in FIGS. 22A through 22C, the bent portions of the elasticsupports 116E were never locked with each other to be unmovable.

The thicknesses of the fixing portion 201, the connection portion 204,and the engagement portion 203 are substantially the same as those inExample 1.

The elastic supports 116, 116A, 116B, 116C, 116D and 116E may beprovided at the four corners of the mask frame 110 as shown in FIG. 20B,such that a similar effect can be provided. In such a case, however, thefixing portion 201 needs to be reduced so as to fit a size of the cornerareas which are relatively small.

EXAMPLE 7

FIG. 8A shows a cathode ray tube 800 in Example 7 according to thepresent invention. FIG. 8B is a cross-sectional view of the cathode raytube 800 shown in FIG. 8A taken along line D—D in FIG. 8A. The cathoderay tube 800 includes a substantially quadrangular panel 803 having aneffective display section 801 and a side wall 802 provided around foursides thereof, and a funnel 805 including a neck 804.

On an inner surface of the effective display section 801 of the panel803, a phosphor screen 806 is provided. The phosphor screen 806 includesthree color phosphor elements respectively providing red (R), green (G)and blue (B) light, which are arranged two-dimensionally. A mask frame810 is engaged with the panel 803 so as to face the phosphor screen 806by a mask frame supporting device described later. The mask frame 810includes a frame 109 and a substantially quadrangular mask 108 attachedto the frame 109. The mask 108 has a gradual curved surface, which has aplurality of electron beam transmission holes (or slits) 807.

FIG. 8C is an isometric view of the mask frame 810. As shown in FIG. 8C,the frame 809 of the mask frame 810 includes two first shafts 809 a andtwo second shafts 809 b. The first shafts 809 a each have an L-shapedcross-section and are formed of an Fe-Cr-Mo alloy. The two second shafts809 b each have a generally U-shaped or polygonal cross-section and areformed of an Fe-Cr-Mo alloy. The first shafts 801 a and the secondshafts 809 b are firmly fixed to each other by welding. The mask 808 iswelded to and extended between the two first shafts 809 a. The frame 809is provided with an inner magnetic shield 811 (FIG. 8A) for shielding anexternal magnetic field such as geomagnetism.

The neck 804 of the funnel 805 accommodates an electron gun 814 foremitting three electron beams 812, and a deflection yoke 813 is providedon an outer surface of the funnel 805. A color image is displayed bydeflecting the three electron beams 812 by a magnetic field generated bythe deflection yoke 813 and horizontally and vertically scanning thephosphor screen 806 with the three electron beams 812 through the mask808.

The mask frame supporting device for engaging the mask frame 810 withthe panel 803 will be described with reference to FIG. 8B. The maskframe supporting device includes stud pins 815 respectively attached tofour inner faces of the side wall 802 of the panel 803, and elasticsupports 816 respectively fixed to the two first shafts 809 a and thetwo second shafts 809 b of the frame 809. Each stud pin 815 is attachedto a substantially central position of the respective inner face of theside wall 802, and each elastic support 816 is fixed to a substantiallycentral position of the respective shaft 809 a or 809 b. The elasticsupports 816 and the stud pins 815 are respectively detachably engagedwith each other.

Referring to FIG. 8C, each elastic support 816 is fixed to therespective shaft 809 a or 809 b by, for example, welding through anattachment plate 817 at a position where the elastic support 816 can beaccurately engaged with a respective stud pin 815. Each attachment plate817 is directly fixed to the respective shaft 809 a or 809 b by welding.

FIG. 9A is a front view of the elastic support 816, and FIG. 9B is aplan view of the elastic support 816. The description below will be doneregarding one elastic support 816 for convenience unless specifiedotherwise.

As shown in FIGS. 9A and 9B, the elastic support 816 is a strip-likeshaped plate having a thickness of about 1.2 mm and is bent at bendingedges 825 and 826. The elastic support 816 includes a fixing portion 819to be fixed to the attachment plate 817, an engagement portion 820having an engaging hole 818 through which the stud pin 115 is inserted,and a connection portion 821 for connecting the fixing portion 819 andthe engagement portion 820 together. The fixing portion 819 and theconnection portion 821 are distinguished from each other by the bendingedge 825, and the connection portion 821 and the engagement portion 820are distinguished from each other by the bending edge 826. The elasticsupport 816 has a bimetal structure including a metal piece 822 formedof a metal having a relatively large coefficient of thermal expansion(for example, stainless steel) and a metal piece 823 formed of a metalhaving a relatively small coefficient of thermal expansion (for example,an Fe-Ni alloy, such as Invar). The metal pieces 822 and 823 aresuperimposed on each other by welding.

During the operation of the cathode ray tube 800, the mask frame 810 isheated and expanded by the scanning of the electron beams 812 (FIG. 8A).In this case, the relative positions between the electron beamtransmission holes 807 and the phosphor screen 806 may be undesirablyshifted from each other by the expansion of the mask frame 810, whichmay cause mislanding of the electron beams 812 (this phenomenon isreferred to as “doming”). At this point, the temperature of the elasticsupports 816 is also raised. Accordingly, the bimetal structure of theelastic supports 816 can adjust the position of the mask frame 810 tocompensate for the doming.

It is not necessary to provide the bending edges 825 and 826. Even inthe structure where no bending edge is provided, the engagement portion820 and the connection portion 821 can be distinguished from the fixingportion 819 as follows. When the stud pin 815 is inserted through theengaging hole 818, an area in the vicinity of the engaging hole 818becomes substantially parallel to the attachment plate 817 due to theelasticity of the elastic support 816. This area can be identified asthe engagement portion 820. The area between the fixing portion 819 andthe engagement portion 820 is inclined with respect thereto. Thisinclined area can be identified as the connection portion 821.

The elastic support 816 includes an elastic portion 824. The elasticportion 824 is a metal plate rolled into a leaf spring shape. One of twoends of the elastic portion 824 is fixed to the fixing portion 819 bywelding. As best shown in FIG. 9B, the elastic portion 824 is sandwichedbetween the fixing portion 819 and the attachment plate 817. The otherend of the elastic portion 824 is constantly in contact with a tip 831of the stud pin 815 when the stud pin 815 is inserted through theengaging hole 818. Accordingly, when the mask frame 810 (FIG. 8A)vibrates in axial directions of the cathode ray tube 800 (in directionsindicated by the two-headed arrow B1 in FIG. 8A, i.e., in directionsperpendicular to the sheet of FIG. 9B) and directions parallel to thesheet of FIG. 9B, tip 831 of the stud pin 815 rubs against the elasticportion 824. At this point, vibration energy is converted into frictionenergy, and thus the vibration of the mask frame 810 is rapidlyattenuated.

The cathode ray tube 800 having the above-described structure wasincorporated into a commercially available TV. Vibration of a speakerwas applied to the cathode ray tube 800 as in Example 1, and nodegradation of color purity was observed. The reason is considered to bethe following. When the mask frame 810 was vibrated due to the vibrationof the speaker, the elastic portion 824 of each elastic support 816rubbed against the tip 831 of a respective stud pin 815, and thefriction between the elastic portion 824 and the tip 831 rapidlyattenuated the vibration, thus preventing degradation of color purity.

Each elastic support 816 has a thickness of about 1 mm or more,preferably about 1.2 mm or more, and in consideration of the practicalspring coefficient and material costs, about 3 mm or less. The elasticportion 824 preferably has a smaller thickness than the other portionsof the elastic support 816 in order to have an appropriate level ofelasticity. The elastic portion 824 preferably has a thickness of about0.05 mm or more and about 0.5 mm or less. The elastic portion 824 mayhave a bimetal structure like the elastic support 816.

A thousand or more cathode ray tubes 800 in Example 7 were produced, andno trouble was experienced in detaching the mask frame 810 from thepanel 803 during the process of forming the phosphor layer, such thatthe yield of the cathode ray tube 800 was 100%.

EXAMPLE 8

In Example 8 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 8A through 8C includes elasticsupports 816A shown in FIGS. 10A and 10B instead of the elastic supports816 shown in FIGS. 9A and 9B. Identical elements previously discussedwith respect to FIGS. 9A and 9B bear identical reference numerals andthe descriptions thereof will be omitted. The description below will bedone regarding one elastic support 816A for convenience unless specifiedotherwise.

The elastic support 816A includes an elastic portion 901 having adifferent structure from that of the elastic portion 824. The elasticportion 901 is a metal plate bent into a leaf spring shape. One of twoends of the elastic portion 901 is fixed to the connection portion 821at a welding point 902 by welding. As in the structure shown in FIG. 9B,when the stud pin 815 is inserted through the engaging hole 818, the tip831 of the stud pin 815 is constantly in contact with the elasticportion 901.

When the mask frame 810 (FIG. 8A) vibrates in directions perpendicularto the sheet of FIG. 10B and directions parallel to the sheet of FIG.10B, the tip 831 of the stud pin 815 rubs against the elastic portion901 to cause friction. Thus, the vibration of the mask frame 810 israpidly attenuated.

The cathode ray tube including the elastic supports 816A wasincorporated into a commercially available TV, and vibration of thespeaker was applied. No degradation of color purity was observed. Thethickness of each portion of the elastic support 816A is the same asthat of the elastic support 816 in Example B.

EXAMPLE 9

In Example 9 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 8A through 8C includes elasticsupports 816B shown in FIGS. 11A and 11B instead of the elastic supports816 shown in FIGS. 9A and 9B. Identical elements previously discussedwith respect to FIGS. 9A and 9B bear identical reference numerals andthe descriptions thereof will be omitted. The description below will bedone regarding one elastic support 816B for convenience unless specifiedotherwise.

The elastic support 816B includes an elastic portion 1001 having adifferent structure from that of the elastic portion 824. The elasticportion 1001 is a metal plate, one of two ends of which is fixed to theengagement portion 820 at a welding point 1002 by welding. As in thestructure shown in FIG. 9B, when the stud pin 815 is inserted throughthe engaging hole 818, the tip 831 of the stud pin 815 is constantly incontact with the elastic portion 901.

When the mask frame 810 (FIG. 8A) vibrates in directions perpendicularto the sheet of FIG. 11B and directions parallel to the sheet of FIG.11B, the tip 831 of the stud pin 815 rubs against the elastic portion1001 to cause friction. Thus, the vibration of the mask frame 810 israpidly attenuated.

The cathode ray tube including the elastic supports 816B wasincorporated into a commercially available TV, and vibration of thespeaker was applied. No degradation of color purity was observed. Thethickness of each portion of the elastic supports 816B is the same asthat of the elastic support 816.

In Examples 1 through 9, the area causing friction is not as large as inthe conventional elastic supports 2001 (FIGS. 23A and 23B) and theelastic portion and the elastic support have different shapes.Accordingly, even small vibration causes friction, such that thevibration restriction effect is satisfactorily large.

EXAMPLE 10

In Example 10 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 8A through 8C includes elasticsupports 816C shown in FIGS. 12A and 12B instead of the elastic supports816 shown in FIGS. 9A and 9B. Identical elements previously discussedwith respect to FIGS. 9A and 9B bear identical reference numerals andthe descriptions thereof will be omitted. The description below will bedone regarding one elastic support 816C for convenience unless specifiedotherwise.

The elastic supports 816C does not include any elastic portion butincludes a plurality of sliding pieces 1101 formed by raising an areasurrounding the engaging hole 818. The plurality of sliding pieces 1101form a funnel shape together. When the stud pin 815 is inserted throughthe engaging hole 818, a side circumferential surface 832 of the studpin 815 is constantly in contact with the plurality of sliding pieces1101.

When the mask frame 810 (FIG. 8A) vibrates in directions in directionsperpendicular to the sheet of FIG. 12B and directions parallel to thesheet of FIG. 12B, the side circumferential surface 832 of the stud pin815 rubs against the plurality of sliding pieces 1101 to cause friction.Thus, the vibration of the mask frame 810 is rapidly attenuated.

The cathode ray tube including the elastic supports 816C wasincorporated into a commercially available TV, and vibration of aspeaker was applied as in Example 10. No degradation of color purity wasobserved. The reason for this is considered to be the following. Whenthe mask frame 810 is vibrated in the axial directions (directionsindicated with the double-headed arrow B1 in FIG. 8A, i.e., thedirections perpendicular to the sheet of FIG. 12B) by the vibration ofthe speaker, the sliding pieces 1101 of each elastic support 816C rubbedagainst the side circumferential surface 832 of a respective stud pin815, and the friction between the sliding pieces 1101 and the sidecircumferential surface 832 rapidly attenuated the vibration, thuspreventing degradation of color purity.

The plurality of sliding pieces 1101 preferably have an identicalthickness as that of the elastic support 816C. Each sliding piece 1101preferably has a length of about 0.5 mm or more and about 2.5 mm orless. When the sliding piece 1101 is shorter than about 0.5 mm, theeffect is reduced. When the sliding piece 1101 is longer than about 2.5mm, the sliding piece 1101 is locked by the stud pin 815 while theelastic support 816C is attached to and detached from the mask frame 810repeatedly, thus undesirably resulting in deformation or destruction ofthe sliding piece 1101.

EXAMPLE 11

In Example 11 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 8A through 8C includes elasticsupports 816D shown in FIGS. 13A and 13B instead of the elastic supports816 shown in FIGS. 9A and 9B. Identical elements previously discussedwith respect to FIGS. 9A and 9B bear identical reference numerals andthe descriptions thereof will be omitted. The description below will bedone regarding one elastic support 816D for convenience unless specifiedotherwise.

The elastic supports 816D includes a fixing portion 819 having an areaS1, an engagement portion 820 having an area S3, and the connectionportion 821 having an area S2. The area S1 of fixing portion 819 islarger than each of the area S3 of the engagement portion 820 and thearea S2 of the connection portion 821. That is, areas S1, S2 and S3satisfy the relationships of S1≧S2 and S1≧S3.

The fixing portion 819 is fixed to the attachment plate 817 by spotwelding at welding points 1204 indicated with an “X” in FIG. 13. Thelocations of the welding points 1204 are determined as follows. Anapproximate half of the fixing portion 819 is defined as an area 1201and another approximate half of the fixing portion 819 is defined as anarea 1202. The welding points 1204 are all located in the area 1201which is farther from the bending edge 825 than the area 1202. The area1201 will be referred to as a “welded area”, and the area 1202 will bereferred to as a “non-welded area”.

The cathode ray tube including the elastic supports 816D wasincorporated into a commercially available TV, and vibration of aspeaker was applied as in Example 1. No degradation of color purity wasobserved. The reason for this is considered to be the following. In thenon-welded area 1202 in which the fixing portion 819 is not welded tothe attachment plate 817, surfaces of the fixing portion 819 and theattachment plate 817 are constantly in contact with each other. When themask frame 810 vibrates the axial directions (directions indicated withthe double-headed arrow B1 in FIG. 8A, i.e., the directionsperpendicular to the sheet of FIG. 13B) and directions parallel to thesheet of FIG. 13B, the contacting surfaces of the fixing portion 819 andthe attachment plate 817 rub against each other in the non-welded area1202 to cause friction. Thus, the vibration of the mask frame 810 israpidly attenuated.

In order to confirm this, a comparative cathode ray tube (not shown;referred to as “cathode ray tube (2)” for convenience) in which theentire fixing portion is welded to the attachment plate was produced andsubjected to the same test. A degradation of color purity was observed.Even after the vibration of the speaker was stopped, the degradation ofcolor purity caused by the vibration of the mask frame was stillobserved for several seconds or longer.

Then, after the cathode ray tube (2) was operated, the mislanding of theelectron beams over-time was measured. 120 minutes after the cathode raytube (2) was turned on, the mislanding was about 70 μm. The cathode raytube including the elastic supports 816D was subjected to the samedoming test. 120 minutes after the cathode ray tube was turned on, themislanding of the electron beams was as small as about 20 μm. The reasonfor this is considered to be the following. In the cathode ray tubeincluding the elastic supports 816D, the distance between the weldedarea 1201 of the elastic support 816D and the engaging hole 818, i.e.,the operating length of the bimetal structure, is relatively long.Accordingly, even a slight temperature rise caused the position of themask frame 810 (FIG. 8A) to be corrected. In the cathode ray tube (2),by contrast, the entire fixing portion 819 is a welded area and thus theoperating length of the bimetal structure is shorter than that of theelastic support 816D. Therefore, the position of the mask frame 810 wasnot sufficiently corrected.

The cathode ray tube including the elastic supports 816D was subjectedto a package dropping test in a similar manner to the manner of Example6. No degradation of color purity was observed.

The area of the welded area 1201 needs to be about 60% or smaller of theentire area of the fixing portion 819 in order to achieve both therestriction of the vibration and the compensation for doming asdescribed above. The area of the welded area 1201 needs to be about 20%or larger of the entire area of the fixing portion 819. When the area ofthe welded area 1201 is smaller than 20% of the entire area of thefixing portion 819, there were cases where the welded area 1201 wasdetached from the attachment plate 817 in the package dropping test.

The same effect can be achieved even when the elastic support 816D isprovided on only each of the second shafts 809 b (FIG. 8B) and anelastic support which does not satisfy the relationships of S1≧S2 andS1≧S3 is provided on each of the first shafts 809 a. The same effect canalso be achieved even when the elastic support 816D is provided on onlyeach of the first shafts 809 a (FIG. 8B) and an elastic support whichdoes not satisfy the relationships of S1≧S2 and S1≧S3 is provided oneach of the second shafts 809 b.

EXAMPLE 12

In Example 12 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 8A through 8C includes elasticsupports 816D shown in FIGS. 13A and 13B, instead of the elasticsupports 816 shown in FIGS. 9A and 9B. Identical elements previouslydiscussed with respect to FIGS. 9A and 9B bear identical referencenumerals and the descriptions thereof will be omitted. The descriptionbelow will be done regarding one elastic support in Example 12 forconvenience unless specified otherwise.

In the elastic support 816D in Example 12, the area S1 of the fixingportion 819, the area S2 of the connection portion 821 and the area S3of the engagement portion 820 satisfy the relationship of S1≧S2≧S3. Inone example, S1=10 cm², S2=8.5 cm², and S3=5 cm². The area S3 does notinclude the area of the engaging hole 818. The area 1201 occupies about40% of the fixing portion 819.

Four elastic supports 816D in Example 12 are respectively located on thetwo first shafts 809 a and two second shafts 809 b of the frame 809(FIG. 8B), each at an approximately central position. The mask frame 810weighs about 4 kg.

The cathode ray tube including the elastic supports 816D in Example 12was incorporated into a commercially available TV, and a packagedropping test was performed as in Example 6. In each of single-colorimages of R, G and B, no degradation of color purity was observed.

For comparison, a comparative cathode ray tube (not shown: referred toas “cathode ray tube (3)” for convenience) including elastic supportswhich are the same as the elastic supports 816D in Example 12 exceptthat the relationship of S1≧S2≧S3 is not satisfied with S1=4.5 cm²,S2=8.5 cm², and S3=5 cm². The comparative cathode ray tube (3) wasincorporated into a commercially available TV and subjected to the samepackage dropping test. In each of single-color images of R, G and Bdisplayed after that, degradation of color purity was observed in aperipheral area of the effective display area. This demonstrates thatmislanding of the electron beams occurred.

In the case of the cathode ray tube including the elastic supports 816Din Example 12, it is considered that even when the mask frame 810significantly swings due to a strong external impact to apply a strongforce to the fixing portion 819 of the elastic support 816D, the maskframe 810 is returned to its original position without the fixingportion 819 being detached from the mask frame 810 or without theelastic support 816D being twisted by plastic deformation at the borderbetween the fixing portion 819 and the connection portion 821.Accordingly, mislanding of the electron beams 812 (FIG. 8A) did notoccur and thus no degradation of color purity occurred.

In the comparative cathode ray tube (3), the fixing portion was detachedfrom the mask frame despite the welding or the elastic support wastwisted by plastic deformation at the border between the fixing portionand the connection portion. Accordingly, the mask frame could not returnto its original position and thus degradation of color purity occurred.

Based on these results, when a strong impact is applied to a cathode raytube from outside, a strong force is applied to the fixing portion ofthe elastic support by the movement of the mask frame. When the area S1of the fixing portion is smaller than the area S3 of the engagement areaor the area S2 of the connection portion, the fixing portion cannotwithstand the force and is detached from the mask frame despite thewelding, or plastic deformation of the elastic support occurs at theborder between the fixing portion and the connection portion. Thus, therelative positions of the mask 808 and the phosphor screen 806 arelikely to be offset. Accordingly, it is important to make the area S1 ofthe fixing portion larger than the area S3 of the engagement portion andalso the area S2 of the connection portion and also to make the area S1of the fixing portion sufficiently large to be strong enough against theweight of the mask frame, in order to prevent mislanding of the electronbeams against an external impact. A necessary area of the fixingportions can be determined in terms of the ratio of the total area ofthe fixing portions 819 (in the case of FIGS. 8A and 8B, 10 cm²×4=40cm²) with respect to the weight of the mask frame 810. Regarding thecathode ray tube in this example, the ratio of about 5 cm²/kg is notpreferable. When the ratio is about 10 cm²/kg or more, degradation ofcolor purity due to mislanding of the electron beams does not occurunless an exceptionally strong force is applied.

EXAMPLE 13

In Example 13 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 8A through 8C includes elasticsupports 816D shown in FIGS. 13A and 13B, instead of the elasticsupports 816 shown in FIGS. 9A and 9B. Identical elements previouslydiscussed with respect to FIGS. 9A and 9B bear identical referencenumerals and the descriptions thereof will be omitted. The descriptionbelow will be done regarding one elastic support in Example 13 forconvenience unless specified otherwise.

In the elastic support 816D in Example 13, S1=5 cm², S2=5 cm², andS3=2.5 cm². S3 does not include the area of the engaging hole 818. Thearea S1 of the fixing portion 819, the area S2 of the connection portion821 and the area S3 of the engagement portion 820 satisfy therelationships of S1≧S2 and S1≧S3. The thickness of the elastic support816D in Example 13 is about 1.2 mm, and the weight of the mask frame 810is about 4 kg.

The cathode ray tube including the elastic supports 816D in Example 13was incorporated into a commercially available TV, and a packagedropping test was performed as described in Example 12. No degradationof color purity due to the mislanding of the electron beams wasobserved.

In the case where the welding surfaces of the fixing portion 819 and theattachment plate 817 were roughened or scratched to have a rough surfaceportion by pressing or filing before welded, no degradation of colorpurity was observed even in a package dropping test with a largeracceleration. The difference of the top and bottom of the rough surfaceis preferably about 10 μm or more and about 500 μm or less.

A preferable ratio of the total area of the fixing portions 819 withrespect to the weight of the mask frame 810 is examined as in Example12. It is considered that the ratio is preferably about 5 cm²/kg ormore, and more preferably about 10 cm²/kg or more.

EXAMPLE 14

In Example 14 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 8A through 8C includes elasticsupports 816E shown in FIG. 14 instead of the elastic supports 816 shownin FIGS. 9A and 9B. Identical elements previously discussed with respectto FIGS. 9A and 9B bear identical reference numerals and thedescriptions thereof will be omitted. The description below will be doneregarding one elastic support 816E for convenience unless specifiedotherwise.

In the elastic support 816E, the area S1 of the fixing portion 819, thearea S2 of the connection portion 821 and the area S3 of the engagementportion 820 do not satisfy the relationship of S1≧S2≧S3. The area S1=7cm², S2=8 cm², and S3=5 cm². S3 does not include the area of theengaging hole 818.

The fixing portion 819 includes bent portions 1301 at both of two endsthereof. The bent portions 1301 are bent towards the attachment plate817. The attachment plate 817 has holes 1302 corresponding to the bentportions 1301. The bent portions 1301 are inserted through the holes1302 and then the fixing portion 819 and the attachment plate 817 arewelded together. The thickness of the elastic support 816E is about 1.3mm, and the weight of the mask frame 810 is about 10 kg.

The cathode ray tube including the elastic supports 816E wasincorporated into a commercially available TV, and a package droppingtest was performed as described in Example 12. No degradation of colorpurity due to the mislanding of the electron beams was observed.

By providing the bent portions 1301 for the elastic support 816E, theresistance against an impact can be increased even though the areas S1,S2 and S3 do not satisfy the relationship of S1≧S2≧S3.

In the case where the bent portions 1301 are inserted through the holes1302 and then the bent portions 1301 are further bent to be parallel tothe attachment plate 817 and welded with the attachment plate 817, theresistance against an impact is further increased.

EXAMPLE 15

In Example 15 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 8A through 8C includes elasticsupports 816F shown in FIGS. 15A and 15B, instead of the elasticsupports 816 shown in FIGS. 9A and 9B, on the second shafts 809 b (FIG.8B). Identical elements previously discussed with respect to FIGS. 9Aand 9B bear identical reference numerals and the descriptions thereofwill be omitted. The description below will be done regarding oneelastic support 816F for convenience unless specified otherwise.

In the elastic support 816F, the area S1 of the fixing portion 819, thearea S2 of the connection portion 821 and the area S3 of the engagementportion 820 satisfy the relationship of S1≧S2≧S3. The area S1=9.5 cm²,S2=9 cm², and S3=3.4 cm². S3 does not include the area of the engaginghole 818. As shown in FIG. 15A, the fixing portion 819 is welded withthe attachment plate (not shown) at welding points 1401 (indicated withan “X”). The welding points 1401 are distributed in an area closer toone end of the fixing portion 819 from the center of the fixing portion819.

The metal piece 822 formed of stainless steel is longer than the metalpiece 823 formed of Invar having a smaller coefficient of thermalexpansion than that of stainless steel. Due to such a structure, themetal piece 822 expands more due to a temperature rise than the casewhere the metal pieces 822 and 823 have the same length. Therefore,satisfactory compensation for doming can be expected.

On the first shafts 809 a (FIG. 8B), the elastic supports having thesame structure as that of the elastic supports 816F except that theareas S1, S2 and S3 do not satisfy the relationship of S1≧S2≧S3. Thearea S1=7 cm², S2=8 cm², and S3=3.4 cm². S3 does not include the area ofthe engaging hole 818. The metal piece 822 formed of stainless steel islonger than the metal piece 823 formed of Invar. The welding points 1401are distributed in an area closer to one end of the fixing portion 819from the center of the fixing portion 819. Both types of elasticsupports have a thickness of about 1.2 mm, and the weight of the maskframe 810 is 4 kg.

The cathode ray tube including the elastic supports as described abovewas incorporated into a commercially available TV, and vibration of aspeaker was applied as in Example 1 to the cathode ray tube. Nodegradation of color purity due to the mislanding of the electron beamswas observed.

The mislanding of the electron beams measured 120 minutes after thecathode ray tube was turned on was as small as about 15 μm. After apackage dropping test performed as in Example 12, no degradation ofcolor purity due to the mislanding of the electron beams was observed.

EXAMPLE 16

In Example 16 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 1A through 1C includes elasticsupports 116F shown in FIGS. 16A and 16B instead of the elastic supports116 shown in FIGS. 2A and 2B. Identical elements previously discussedwith respect to FIGS. 2A and 2B bear identical reference numerals andthe descriptions thereof will be omitted. The description below will bedone regarding one elastic support 116F for convenience unless specifiedotherwise.

As best shown in FIG. 16B, the elastic support 116F has a V-shapedcross-section. When the mask frame 110 (FIG. 1A) is heated and expandedby the scanning of the electron beams 112 during the operation of thecathode ray tube, the frame 109 presses the elastic supports 116Ftowards the side wall 102, which may undesirably offsets the relativepositions of the electron beams 112 and the phosphor screen 106. Theelastic support 116F has a V-shaped cross-section in order toautomatically adjust the position of the mask frame 110 so thatmislanding of the electron beams are prevented.

The elastic support 116F shown in FIGS. 16A and 16B includes a fixingportion 1501 having an area S1, an engagement portion 1503 having anarea S3 and having an engaging hole 1502, and a connection portion 1503having an area S2 and having a hole 1505. S1=22.5 cm², S2=4.5 cm², andS3=5 cm². S1 is the area which is in contact with the frame 109 b or theattachment plate 117 (FIG. 1C), S2 does not include the area of the hole1505, and S3 does not include the area of the engaging hole 1502. S1, S2and S3 fulfill the relationships of S1≧S2 and S1≧S3. The fixing portion1501 has a thickness of about 1 mm, and the connection portion 1504 andthe engagement portion 1503 each have a thickness of about 0.5 mm. Theweight of the mask frame 110 (FIG. 1A) is about 6.4 kg. The weldingpoints 1511 of the fixing portion 1501 with the frame 109 or theattachment plate 117 are indicated with an “X”. The welding points 1511are distributed in areas closer to both of two ends 1506 of the fixingportion 1501 from the connection portion 1504.

The cathode ray tube including the elastic supports 116F wasincorporated into a commercially available TV, and vibration of aspeaker was applied as in Example 1. No degradation of color purity wasobserved. This is considered to be because vibration of the frame 110was rapidly attenuated due to the friction between the fixing portion1501 and the frame 109 in the area where the fixing portion 1501 is notwelded to the frame 109.

A package dropping test was performed as in Example 12, and nodegradation of color purity was observed.

For comparison, a comparative cathode ray tube (not shown; referred toas “cathode ray tube (4)” for convenience) including elastic supportswhich are the same as the elastic supports in Example 16 except thatS1=7.5 cm², S2=8.0 cm² and S3=6.5 cm². The comparative cathode ray tube(4) was incorporated into a commercially available TV and subjected to apackage dropping test. In each of single-color images of R, G and Bdisplayed after that, degradation of color purity was observed in aperipheral area of the effective display area. This demonstrates thatmislanding of the electron beams occurred.

The elastic support 116F in Example 16 provides the same effect in thecase where the thickness of the fixing portion 1501 is more than about 1mm, and the thickness of each of the connection portion 1504 and theengagement portion 1503 is about 0.3 mm or more and about 0.9 mm orless.

EXAMPLE 17

In Example 17 according to the present invention, cathode ray tubeshaving the structure shown in FIGS. 1A through 1C including the elasticsupports having the structure of elastic supports 116F shown in FIGS.16A and 16B were produced with the area S1 of the fixing portion 1501being changed from 5 cm², 10 cm², 15 cm², to 20 cm². Ten cathode raytubes were produced for each size of the fixing portion 1501. Thecathode ray tubes were each incorporated into a commercially availableTV and subjected to a package dropping test. The results are shown inTable 1.

TABLE 1 CRT Sample No. 3 4 5 6 Area of fixing 5 10 15 20 portion (S1)Ratio of 100 10 0 0 generation of degradation of color purity

Based on the result shown in Table 1, it is understood that when thearea S1 is 7.5 cm² or less, the ratio of generation of degradation ofcolor purity is unacceptably high; when the area S1 is 10 cm² or more,the ratio of generation of degradation of color purity is 10% or lessand acceptable; and when the area S1 is 15 cm² or more, there is noproblem regarding the degradation of color purity.

As in Example 12, the total area of the fixing portions 1501 of theelastic supports 116F (in the case of FIG. 1B, S1×4) with respect to theweight of the mask frame 110 (FIG. 1A; 6.4 kg) is preferably about 5cm²/kg or more and more preferably about 10 cm²/kg or more, based on theresults shown in Table 1 and Example 16. Using this as a reference, anappropriate total area of the fixing portions can be found with respectto a mask frame of any weight.

EXAMPLE 18

In Example 18 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 1A through 1C includes elasticsupports 116G shown in FIGS. 17A and 17B instead of the elastic supports116 shown in FIGS. 2A and 2B. Identical elements previously discussedwith respect to FIGS. 2A and 2B and 16A and 16B bear identical referencenumerals and the descriptions thereof will be omitted. The descriptionbelow will be done regarding one elastic support 116G for convenienceunless specified otherwise.

As best shown in FIG. 17B, the elastic support 116G includes a flatfixing portion 1601 including an area 1601 a welded with the connectionportion 1504. The elastic support 116G has a cuneiform cross-section.The welding points are indicated with an “X” in FIG. 17A. The weight ofthe mask frame 110 is 8 kg.

The cathode ray tubes in Example 18 including the elastic supports 116Gshown in FIGS. 17A and 17B were produced with the area S1 of the fixingportion 1501 being changed from 5 cm², 10 cm², 15 cm², to 20 cm². Twentycathode ray tubes were produced for each size of the fixing portion1601. The cathode ray tubes were each incorporated into a commerciallyavailable TV and subjected to a package dropping test as in Example 12.The results are shown in Table 2.

TABLE 2 CRT Sample No. 7 8 9 10 Area of fixing 5 10 15 20 portion (S1)Ratio of 100 15 0 0 generation of degradation of color purity

The total area of the fixing portions 1601 of the elastic supports 116Gwith respect to the weight of the mask frame 110 (FIG. 1A) is preferablyabout 5 cm²/kg or more based on the results shown in Table 1, morepreferably about 7.5 cm²/kg or more.

EXAMPLE 19

In Example 19 according to the present invention, a cathode ray tubehaving the structure shown in FIGS. 1A through 1C includes elasticsupports 116H shown in FIG. 18 provided on the first shafts 109 a (FIG.1B). Along the second shafts 109 b, the elastic supports 116F shown inFIGS. 16A and 16B are provided. The elastic description below will bedone regarding one elastic support 116H for convenience unless specifiedotherwise.

The elastic support 116H includes a fixing portion 1501 including bentportions 1701 at both of two ends thereof. The bent portions 1701 arebent towards attachment plate 117. The fixing portion 1501 has an areaS1 of 10 cm² (Table 1, sample no. 4). The attachment plate 117 has holes1702 corresponding to the bent portions 1701.

The bent portions 1501 are inserted through the holes 1702, further bentoutwards or inwards to be parallel to the attachment plate 117 andwelded with the attachment plate 117. The remaining part of the fixingportion 1501 is fixed to the attachment plate 117 by welding.

Twenty cathode ray tubes in Example 19 were produced and eachincorporated into a commercially available TV and subjected to a packagedropping test as in Example 12. The ratio of generation of degradationof color purity was 0%.

EXAMPLE 20

Example 20 according to the present invention is directed to the cathoderay tube shown in FIGS. 8A through 8C including the elastic supportsshown in FIGS. 13A and 13B and described in Example 11, 12 or 13. Ineach of these cathode ray tubes, the spring coefficient or the distancebetween the frame 809 and the stud pin 815 was changed so that the forceof the stud pin 815 pressing the elastic support 816D through theengaging hole 818 was changed so as to be different for each of the fourelastic supports 816D. The pressing force was not to exceed the rangefrom about 5 N (newton) to about 100 N including about 5 N and about 100N. When the force is less than 5 N, the engagement of the stud pin 815and the engaging hole 818 is unstable, and when the force is more than100 N, the force undesirably influences the shape of the frame 809.

The cathode ray tubes produced in this manner were each incorporatedinto a commercially available TV and vibration of a speaker was appliedas in Example 1. The vibration amplitude was smaller than the case wherethe frame 809 is pressed by the same force at the four sides thereof.This is considered to have occurred for the following reason. Since thepressing force is different for each of the four sides, the internalstress is also different for each of the four sides. As a result, theresonance frequency is different for each of the four elastic supports816D. Accordingly, the vibration of the frame 809 is constantlyattenuated by at least one of the elastic supports 816D. Thus, resonanceof the elastic supports 816D and the frame 809 is alleviated.

In the above example, the pressing force is made to be different foreach of the four elastic supports 816D. Instead, the pressing forceapplied to the elastic supports 816D provided along the first shafts 809a can be made to be different from the pressing force applied to theelastic supports 816D provided on the second shafts 809 b. In this case,it is effective to make the pressing force applied to the elasticsupports 816D provided on the second shafts 809 b 1.1 to 3 times largerthan the pressing force applied to the elastic supports 816D provided onthe first shafts 809 a in order to alleviate a twisting vibration of theframe 809.

In order to set the pressing force in the above-described range, thespring coefficient of each elastic support 816D is preferably about 1N/mm or more and about 25 N/mm or less. When the spring coefficient isless than about 1 N/mm, the rigidity of the elastic support 816D is toosmall to maintain the strength to engage the frame 809. When the springcoefficient is more than about 25 N/mm, the rigidity of the elasticsupport 816D is excessively strong and has an adverse influence onproduction.

EXAMPLE 21

Example 21 according to the present invention is directed to the cathoderay tube 100 shown in FIGS. 1A through 1C and respectively including theelastic supports 116F shown in FIGS. 16A and 16B described in Example 16or the elastic supports 116H shown in FIG. 18A described in Example 19.In each of these cathode ray tubes, the relationship between thepressing force applied to the elastic supports and the vibration of theframe 109 was examined as described in Example 20. The same results asthose in Example 20 were obtained.

In each of Examples 1 through 21, the mask main body, the frame and theelastic supports may be formed of other metals than those described inorder to provide a similar effect. The number of the elastic supportsprovided to the frame is not limited to four, and may be three, five ormore. The position at which each elastic support is attached is notlimited to the center of the sides or the corners, and may be anyposition on a side. The elastic portion of the elastic support is notlimited to be formed of one plate, and may be formed of a plurality ofplates which are superimposed on one another. The elastic portion is notlimited to have a flat surface, and may include a curved surface.

Each of the masks 108 and 808 may be a press mask, an aperture grill, ora shadow mask extended between the respective first shafts 109 a and 809a of the frame.

FIG. 19 shows one example of a shadow mask 1801. When the shadow mask1801 is used, it is effective to provide dampers 1802 for attenuatingvibration of the shadow mask 1801 along both of two longer sides of theshadow mask 1801. Reference numeral 1804 represents a first shaft of theframe, and reference numeral 1805 represents a second shaft of the framewhich is shorter than the first shaft 1804. For the sake of convenience,the elastic supports are not shown in FIG. 19.

Each damper 1802 is formed simply by making holes 1803 in the vicinityof the side of the shadow mask 1801 and inserting a wire through theholes 1803. It is preferable that the damper 1802 is formed of amaterial having a larger coefficient of thermal expansion than thematerial of the shadow mask 1801 since the temperature rise of thedamper 1802 is slightly delayed from the temperature rise of the shadowmask 1801. In order to cause the damper 1802 to function effectively, itis necessary to make the vibration amplitude large at the four sides ofthe shadow mask 1801. In order to achieve this, the shadow mask 1801preferably has a tension distribution which is largest in a central areaof the shadow mask 1801 and becomes smaller towards the four sides ofthe shadow mask 1801.

In order to restrict the temperature rise in the mask 108, 808 shownrespectively in FIGS. 1A, 8A, it is preferable to coat a surface of themask 108, 808 facing the electron gun 114, 814 with a material having asufficiently large mass number such as Bi (bismuth) or the like. In thiscase, a part of each of the electron beams which is not transmittedthrough the hole 107, 807 is reflected by the surface of the mask 108,808, which effectively reduces doming.

As a cathode used for the electron gun 114, 814 (FIGS. 1A, 8A), a hotcathode is common. It is preferable to use an electric field electronemission element (cold cathode) for reducing the diameter of theelectron beams in order to provide the effect of the present inventionmore noticeably for the following reason. When the diameter of theelectron beams is smaller, an image having a higher resolution can bedisplayed. An image having a higher resolution requires a higherresistance against vibration and a higher resistance against the effectsof dropping. With the structure of the conventional cathode ray tube,such a high resistance against vibration or the effects of droppingcannot be provided and degradation of color purity is inevitable. Bycontrast, a cathode ray tube according to the present invention has beenconfirmed not to cause degradation of color purity when externalvibration is applied to the cathode ray tube or even the cathode raytube in the case where the cold cathode is used. An electron source forthe cold cathode may be, for example, a Spindt-type or tower-typeelectron source formed of Mo, Nb, W, Si, SiC or the like; an electronsource formed of a carbon-based emitter including carbon nanotubes,graphite nanofibers, diamond, carbon fibers or the like; or an electronsource formed of an emitter having a negative electron affinity formedof aluminum nitride (AlN) or the like.

As described above, according to a cathode ray tube of the presentinvention, degradation of color purity due to mislanding of the electronbeams does not occur even when external vibration or strong impact isapplied to the cathode ray tube.

INDUSTRIAL APPLICABILITY

The present invention provides an effect of providing a cathode ray tubewhich prevents degradation of color purity due to mislanding of theelectron beams even when external vibration or strong impact is applied.

1. A cathode ray tube, comprising: an electron gun for emitting at least one electron beam; a mask frame include a mask having a plurality of holes or slits for allowing the at least one electron beam to be transmitted therethrough and a frame to which the mask is attached; and a panel including a phosphor layer to be scanned by the at least one electron beam transmitted through the plurality of holes or slits of the mask, wherein: the panel includes a plurality of stud pins for supporting the frame; the frame includes a plurality of elastic supports engaged with the plurality of stud pins; at least one of the plurality of elastic supports includes an engagement portion having an engaging hole which is engaged with one of the plurality of the stud pins and an elastic portion in contact with the one stud pin, wherein the at least one elastic support includes a fixing portion for fixing the at least one elastic support to the frame, and the elastic portion is fixed to the fixing portion, and the at least one elastic support further includes a connection portion for connecting the fixing portion and the engagement portion to each other; and mask frame vibration causes the elastic portion to rub against a respective stud pin so as to generate a frictional force for attenuating the vibration of the mask frame.
 2. A cathode ray tube according to claim 1, wherein the one stud pin has a tip, and the elastic portion rubs against the tip of the one stud pin.
 3. A cathode ray tube according to claim 1, wherein the elastic portion is formed of a metal plate rolled into a cylindrical shape.
 4. A cathode ray tube according to claim 1, wherein the elastic portion is formed of a metal plate bent into a leaf spring-shape.
 5. A cathode ray tube according to claim 1, wherein the fixing portion is provided between the engagement portion and the frame.
 6. A cathode ray tube according to claim 5, wherein the elastic portion is provided between the engagement portion and the fixing portion.
 7. A cathode ray tube according to claim 1, wherein a thickness of the fixing portion t0, a thickness of the connection portion t1 and a thickness of the elastic portion t2 satisfy the relationships of t0>t1 and t0>t2.
 8. A cathode ray tube according to claim 1, wherein a thickness of the fixing portion t0, a thickness of the connection portion t1 and a thickness of the elastic portion t2 satisfy the relationships of t0>t1 and t1>t2.
 9. A cathode ray tube according to claim 1, wherein each of the plurality of elastic supports has a substantially V-shaped cross-section.
 10. A cathode ray tube according to claim 1, wherein each of the plurality of elastic supports has a substantially strip-like shape.
 11. A cathode ray tube according to claim 1, wherein the at least one elastic support further includes a connection portion for connecting the fixing portion and the engagement portion to each other, and the elastic portion is fixed to the connection portion.
 12. A cathode ray tube according to claim 1, wherein the elastic portion is fixed to the engagement portion.
 13. A cathode ray tube according to claim 1, wherein the frame includes a pair of first shafts and a pair of second shafts shorter than the pair of first shafts, and the at least one elastic support is provided on at least one first shaft of the pair of first shafts.
 14. A cathode ray tube according to claim 1, wherein the frame includes a pair of first shafts and a pair of second shafts shorter than the pair of first shafts, and the at least one elastic support is provided on at least one second shaft of the pair of second shafts.
 15. A cathode ray tube according to claim 1, wherein the frame includes a plurality of corners, and the plurality of elastic supports are provided at respective corners.
 16. A cathode ray tube according to claim 1, wherein the mask includes a damper provided at an end thereof for attenuating the vibration of the mask.
 17. A cathode ray tube according to claim 1, wherein the electron gun includes an electric field electron emission element for reducing a cross-section of the at least one electron beam.
 18. A cathode ray tube according to claim 1, wherein the at least one elastic support has a bimetal structure including a first metal area formed of a first metal having a first coefficient of thermal expansion and a second metal area formed of a second metal having a second coefficient of thermal expansion which is less than the first coefficient of thermal expansion, the first metal area and the second metal being joined together.
 19. A cathode ray tube according to claim 18, wherein the first metal area formed of the first metal has a greater longitudinal size than a longitudinal size of the second metal area formed of the second metal.
 20. A cathode ray tube according to claim 18, wherein the first metal includes stainless steel, and the second metal includes nickel steel.
 21. An image display apparatus including a cathode ray tube according to claim
 1. 22. A cathode ray tube, comprising: an electron gun for emitting at least one electron beam; a mask frame include a mask having a plurality of holes or slits for allowing the at least one electron beam to be transmitted therethrough and a frame to which the mask is attached; and a panel including a phosphor layer to be scanned by the at least one electron beam transmitted through the plurality of holes or slits of the mask, wherein: the panel includes a plurality of stud pins for supporting the frame; the frame includes a plurality of elastic supports engaged with the plurality of stud pins; at least one of the plurality of elastic supports includes an engagement portion having an engaging hole which is engaged with one of the plurality of stud pins; the engagement portion includes a plurality of sliding pieces forming a funnel shape provided in the engaging hole; and mask frame vibration causes a surface of each of the plurality of sliding pieces to rub against a respective stud pin so as to generate a frictional force for attenuating the vibration of the mask frame.
 23. A cathode ray tube according to claim 22, wherein the at least one elastic support includes a fixing portion for fixing the at least one elastic support to the frame, and a connection portion for connecting the fixing portion and the engagement portion.
 24. A cathode ray tube according to claim 23, wherein the sliding piece has a length of about 0.5 mm or more and about 2.5 mm or less.
 25. A cathode ray tube according to claim 22, wherein each of the plurality of elastic supports has a substantially strip-like shape.
 26. A cathode ray tube according to claim 22, wherein the mask includes a damper provided at an end thereof for attenuating the vibration of the mask.
 27. A cathode ray tube according to claim 22, wherein the electron gun includes an electric field electron emission element for reducing a cross-section of the at least one electron beam.
 28. An image display apparatus including a cathode ray tube according to claim
 22. 29. A cathode ray tube, comprising: an electron gun for emitting at least one electron beam; a mask frame include a mask having a plurality of holes or slits for allowing the at least one electron beam to be transmitted therethrough and a frame to which the mask is attached; and a panel including a phosphor layer to be scanned by the at least one electron beam transmitted through the plurality of holes or slits of the mask, wherein: the panel includes a plurality of stud pins for supporting the frame; the frame includes a plurality of elastic supports engaged with the plurality of stud pins; at least one of the plurality of elastic supports includes an engagement portion having an engaging hole which is engaged with one of the plurality of stud pins; the engagement portion includes a central portion having the engaging hole, a first side portion separated from the central portion by a first cut, and a second side portion separated from the central portion by a second cut formed on an opposite side to the first cut with respect to the central portion; mask frame vibration causes a cut sectional face of the central portion facing the first cut to rub against a cut sectional face of the first side portion so as to generate a frictional force for attenuating the vibration of the mask frame; and mask frame vibration further causes another cut sectional face of the central portion facing the second cut to rub against a cut sectional face of the second side portion so as to generate a frictional force for attenuating the vibration of the mask frame.
 30. A cathode ray tube according to claim 29, wherein the at least one elastic support includes a fixing portion for fixing the at least one elastic support to the frame, and a connection portion for connecting the fixing portion and the engagement portion to each other.
 31. A cathode ray tube according to claim 29, wherein each of the plurality of elastic supports has a substantially V-shaped cross-section.
 32. A cathode ray tube according to claim 29, wherein the mask includes a damper provided at an end thereof for attenuating the vibration of the mask.
 33. A cathode ray tube according to claim 29, wherein the electron gun includes an electric field electron emission element for reducing a cross-section of the at least one electron beam.
 34. An image display apparatus including a cathode ray tube according to claim
 29. 35. A cathode ray tube, comprising: an electron gun for emitting at least one electron beam; a mask frame including a mask having a plurality of holes or slits for allowing the at least one electron beam to be transmitted therethrough and a frame to which the mask is attached; and a panel including a phosphor layer to be scanned by the at least one electron beam transmitted through the plurality of holes or slits of the mask, wherein: the panel includes a plurality of stud pins for supporting the frame: the frame includes a plurality of elastic supports engaged with the plurality of stud pins; at least one of the plurality of elastic supports includes an engagement portion having an engaging hole which is engaged with one of the plurality of stud pins and a fixing portion for fixing the at least one elastic support to the frame; the fixing portion includes a first bent portion and a second bent portion bent towards the engagement portion; the first bent portion has a fifth bent portion for restricting the engagement portion from moving in a direction away from the fixing portion, and the second bent portion has a sixth bent portion for restricting the engagement portion from moving towards the fixing portion, the engagement portion includes a third bent portion bent so as to be in contact with the first bent portion and a fourth bent portion bent so as to be in contact with the second bent portion; mask frame vibration causes the first bent portion to rub against the third bent portion so as to generate a frictional force for attenuating the vibration of the mask frame; and the mask frame vibration further causes the second bent portion to rub against the fourth bent portion so as to generate a frictional force for attenuating the vibration of the mask frame.
 36. A cathode ray tube according to claim 35, wherein the at least one elastic support further includes a connection portion for connecting the fixing portion and the engagement portion to each other.
 37. A cathode ray tube according to claim 35, wherein each of the plurality of elastic supports has a substantially V-shaped cross-section.
 38. A cathode ray tube according to claim 35, wherein the frame includes a plurality of corners, and the plurality of elastic supports are provided at respective corners.
 39. A cathode ray tube according to claim 35, wherein the frame includes a pair of first shafts and a pair of second shafts shorter than the pair of first shafts, and the at least one elastic support is provided on at least one first shaft of the pair of first shafts.
 40. A cathode ray tube according to claim 35, wherein the frame includes a pair of first shafts and a pair of second shafts shorter than the pair of first shafts, and the at least one elastic support is provided on at least one second shaft of the pair of second shafts.
 41. A cathode ray tube according to claim 35, wherein the mask includes a damper provided at an end thereof for attenuating the vibration of the mask.
 42. A cathode ray tube according to claim 35, wherein the electron gun includes an electric field electron emission element for reducing a cross-section of the at least one electron beam.
 43. An image display apparatus including a cathode ray tube according to claim
 35. 44. A cathode ray tube, comprising: an electron gun for emitting at least one electron beam; a mask frame include a mask having a plurality of holes or slits for allowing the at least one electron beam to be transmitted therethrough and a frame to which the mask is attached; and a panel including a phosphor layer to be scanned by the at least one electron beam transmitted through the plurality of holes or slits of the mask, wherein: the panel includes a plurality of stud pins for supporting the frame; the frame includes a plurality of elastic supports engaged with the plurality of stud pins; at least one of the plurality of elastic supports includes an engagement portion having an engaging hole which is engaged with one of the plurality of stud pins and an elastic portion in contact with the engagement portion, wherein the at least one elastic support includes a fixing portion for fixing the at least one elastic support to the frame, and the elastic portion is fixed to the fixing portion, and the at least one elastic support further includes a connection portion for connecting the fixing portion and the engagement portion to each other; and mask frame vibration causes the elastic portion to rub against the engagement portion so as to generate a frictional force for attenuating the vibration of the mask frame.
 45. A cathode ray tube according to claim 44, wherein the elastic portion is provided on each of both sides of the engaging hole.
 46. A cathode ray tube according to claim 44, wherein the elastic portion is a metal plate rolled into a cylindrical shape.
 47. A cathode ray tube according to claim 44, wherein the elastic portion is formed of a metal plate bent into a leaf spring-shape.
 48. A cathode ray tube according to claim 44, wherein each of the plurality of elastic supports has a substantially V-shaped cross-section.
 49. A cathode ray tube according to claim 44, wherein the mask includes a damper provided at an end thereof for attenuating the vibration of the mask.
 50. A cathode ray tube according to claim 44, wherein the electron gun includes an electric field electron emission element for reducing a cross-section of the at least one electron beam.
 51. An image display apparatus including a cathode ray tube according to claim
 44. 